Pyridazine derivatives and their use as therapeutic agents

ABSTRACT

Methods of treating an SCD-mediated skin disorder or condition in a mammal, preferably a human include administering to a mammal in need thereof a compound of formula (I): 
                         
where x, y, W, V, R 2 , R 3 , R 4 , R 5 , R 6 , R 6a , R 7 , R 7a , R 8 , R 8a , R 9  and R 9a  are defined herein.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part (CIP) application and claims benefit under 35 U.S.C. §120 of U.S. patent application Ser. No. 10/901,563 filed on Jul. 29, 2004, which claims the benefit of U.S. Provisional Patent Application Ser. No. 60/491,095, filed Jul. 30, 2003; U.S. Provisional Patent Application Ser. No. 60/546,820, filed Feb. 23, 2004; U.S. Provisional Patent Application Ser. No. 60/553,416, filed Mar. 16, 2004; U.S. Provisional Patent Application Ser. No. 60/546,934, filed Feb. 23, 2004; U.S. Provisional Patent Application Ser. No. 60/553,446, filed Mar. 16, 2004; U.S. Provisional Patent Application Ser. No. 60/546,786, filed Feb. 23, 2004; U.S. Provisional Patent Application Ser. No. 60/553,403, filed Mar. 16, 2004; U.S. Provisional Patent Application Ser. No. 60/546,898, filed Feb. 23, 2004; U.S. Provisional Patent Application Ser. No. 60/553,404, filed Mar. 16, 2004; U.S. Provisional Patent Application Ser. No. 60/546,815, filed Feb. 23, 2004; and U.S. Provisional Patent Application Ser. No. 60/553,491, filed Mar. 16, 2004. These prior applications are hereby incorporated by reference in their entireties.

FIELD OF THE INVENTION

The present invention relates generally to the field of inhibitors of stearoyl-CoA desaturase, such as pyridazine derivatives, and uses of such compounds in treating and/or preventing various diseases mediated by stearoyl-CoA desaturase (SCD), especially skin disorders such as acne, rosacea, and seborrheic skin.

BACKGROUND OF THE INVENTION

Skin comprises three primary layers: epidermis, dermis, and hypodermis. In addition, animal skins are often covered with hairs, which are produced by hair follicles structures. FIG. 1 shows a schematic illustration of a section of a skin with a follicle structure 10. As shown, a hair follicle 12 is associated with sebaceous glands 11, which can deposit sebum 13 on the hairs 15. The sebum eventually rises to the skin surface 15 along the hair shaft. Sebaceous glands are also found in non-haired areas (glabrous skin) such as eyelids. In the non-haired areas, the sebum traverses ducts which terminate in sweat pores on the surface of the skin. The sebaceous glands at the rim of the eyelids are called meibomian glands; they secrete sebum into the tears coating the eye, to slow evaporation.

Sebum is made of fat (lipids) and the debris of dead fat-producing cells. In the sebaceous glands, sebum is produced within specialized cells and is released as these cells burst. Sebum protects and waterproofs hair and skin, keeping them from becoming dry, brittle and cracked. It also inhibits the growth of microorganisms on skin. However, excess secretion of sebum may give rise to skin disorders, such as acne and keratosis pilaris. Medications for treating such skin diseases are available. For example, isotretinoin (a vitamin A analog) can significantly reduce the amount of sebum produced by the sebaceous glands and may be used to treat acne. Isotretinoin may be used orally (such as Accutane® from Roche) or topically (such as Isotrex® or Isotrexin® from Stiefel). The precise mechanism of isotretinoin's action is unknown, though its action is thought to be mediated by its effects on cellular transcription.

The compositions of sebum vary from species to species. In humans, the lipid content is as follows: wax monoesters (25%), triglycerides (41%), free fatty acids (16%), and squalenes (12%). See, J. B. Cheng et al., “Mammalian Wax Biosynthesis II: Expression Cloning of Wax Synthase cDNAs Encoding a Member of the Acyltransferase Enzyme Family,” J. Biol. Chem., 2004 Sep. 3; 279(36):37798-37807. Thus, fats and fatty acids are the main components of sebum. Accordingly, manipulating fat production in sebaceous glands may offer an approach to the control of sebum production, and hence a way to treat or prevent skin disorders associated with excess sebum production.

Acyl desaturases are critical enzymes involved in the synthesis of fats or lipids. They catalyze the formation of double bonds in fatty acids. Mammals synthesize at least three fatty acid desaturases having differing chain length specificity that catalyze the formation of double bonds at the 9, 6, and 5 positions. Stearoyl-CoA desaturases (SCDs) introduce a double bond at the C9-C10 position of saturated fatty acids. The preferred substrates for SCDs are palmitoyl-CoA (16:0) and stearoyl-CoA (18:0), which are converted to palmitoleoyl-CoA (16:1) and oleoyl-CoA (18:1), respectively. The resulting mono-unsaturated fatty acids are substrates for incorporation into phospholipids, triglycerides, and cholesteryl esters.

A number of mammalian SCD genes have been cloned. For example, two genes have been cloned from rat (SCD1, SCD2) and four SCD genes have been isolated from mouse (SCD1, 2, 3, and 4). A single SCD gene, SCD1, has been characterized in humans (Brownlie et al. PCT application, WO 01/62954). A second human SCD isoform has recently been identified (PCT application, WO 02/26944). Because this isoform bears little sequence homology to other mouse or rat isoforms, it has been named human SCD5 or hSCD5.

Basic biochemical roles of SCD have been known in rats and mice for some time (Jeffcoat, R. et al., Elsevier Science (1984), Vol. 4, pp. 85-112; de Antueno, R J, Lipids (1993), Vol. 28, No. 4, pp. 285-290). They have also been implicated in human disease processes. For example, abnormal SCD1 activity has been linked to skin disorders. Zheng, et al., Nat. Genet. (1999) 23:268-270, show that rodents lacking a functional SCD gene have reduced sebum production and associated changes in the conditions of their eyes, skin and coat. In addition, Miyazaki, et al., J. Nutr. (2001), Vol. 131, pp 2260-2268, noted that SCD1−/− mice develop cutaneous abnormalities, associated with atrophic sebaceous and meibomian glands. These observations suggest a possibility of treating or preventing skin disorders that are associated with excess sebum productions, such as acne, rosacea, and seborrheic skin, by inhibiting SCD activities.

To date, no small-molecule, drug-like compounds are known that specifically inhibit or modulate SCD activities. Certain long-chain fatty-acid analogs have been found to inhibit SCD activities, presumably by competing with substrates in the active sites of these enzymes. For example, cis-12, trans-10 conjugated linoleic acid can inhibit SCD activity and reduce the abundance of SCD1 mRNA. Cyclopropenoid fatty acids, such as those found in stercula and cotton seeds, can also inhibit SCD activity, including sterculic acid (8-(2-octylcyclopropenyl)-octanoic acid) and malvalic acid (7-(2-octylcyclopropenyl)heptanoic acid), which are C18 and C16 analogs of sterculoyl and malvaloyl fatty acids, respectively, having cyclopropene rings at their C9-C10 positions. Other agents that may inhibit SCD include thia-fatty acids, e.g., 9-thiastearic acid (also called 8-nonylthiooctanoic acid) and other fatty acids with a sulfoxy moiety.

These known modulators of delta-9 desaturase activity are not useful for treating diseases and disorders linked to SCD1 because they are neither useful at reasonable doses, nor specific inhibitors of SCD1. Instead, they demonstrate cross inhibition of other desaturases, in particular the delta-5 and delta-6 desaturases.

The absence of small molecule inhibitors of SCD is a major scientific and medical disappointment because evidence is now compelling that SCD activity is directly implicated in various human disease processes (including skin diseases): See e.g., Attic, A. D. et al., “Relationship between stearoyl-CoA desaturase activity and plasma triglycerides in human and mouse hypertriglyceridemia”, J. Lipid Res. (2002), Vol. 43, No. 11, pp. 1899-907; Cohen, P. et al., “Role for stearoyl-CoA desaturase-1 in leptin-mediated weight loss”, Science (2002), Vol. 297, No. 5579, pp. 240-3, Ntambi, J. M. et al, “Loss of stearoyl-CoA desaturase-1 function protects mice against adiposity”, Proc. Natl. Acad. Sci. USA. (2002), Vol. 99, No. 7, pp. 11482-6.

As noted above, inhibitors of SCD may be useful in the treatment or prevention of skin disorders such as acne, rosacea, and seborrheic skin. Although other medications for acne are available, there is still a need for therapeutic agents that treat these skin disorders by different mechanisms.

BRIEF SUMMARY OF THE INVENTION

The present invention provides methods for treating or preventing skin disorders using pyridazine derivatives that modulate the activity of stearoyl-CoA desaturase.

In one aspect, methods of the invention use compounds of formula (I),

wherein:

x and y are each independently 1, 2 or 3;

W is —C(O)N(R¹)—; —C(O)N[C(O)R^(1a)]—, —N(R¹)C(O)N(R¹¹)— or —N(R¹)C(O)—;

V is —C(O)—, —C(S)—, or —C(R¹⁰)H;

each R¹ is independently selected from the group consisting of hydrogen; C₁-C₆alkyl optionally substituted with one or more substituents selected from the group consisting of halo, methyl or trifluoromethyl; and C₂-C₆alkyl optionally substituted with one or more substituents selected from the group consisting of methoxy and hydroxyl;

R^(1a) is selected from the group consisting of hydrogen, C₁-C₆alkyl and cycloalkyl;

R² is selected from the group consisting of C₁-C₁₂alkyl, C₂-C₁₂alkenyl, C₂-C₁₂hydroxyalkyl, C₂-C₁₂hydroxyalkenyl, C₁-C₁₂alkoxy, C₂-C₁₂alkoxyalkyl, C₃-C₁₂cycloalkyl, C₄-C₁₂cycloalkylalkyl, aryl, C₇-C₁₂aralkyl, C₃-C₁₂heterocyclyl, C₃-C₁₂heterocyclylalkyl, C₁-C₁₂heteroaryl, and C₃-C₁₂heteroarylalkyl;

or R² is a multi-ring structure having 2 to 4 rings wherein the rings are independently selected from the group consisting of cycloalkyl, heterocyclyl, aryl and heteroaryl and where some or all of the rings may be fused to each other;

R³ is selected from the group consisting of C₁-C₁₂alkyl, C₂-C₁₂alkenyl, C₂-C₁₂hydroxyalkyl, C₂-C₁₂hydroxyalkenyl, C₁-C₁₂alkoxy, C₂-C₁₂alkoxyalkyl, C₃-C₁₂cycloalkyl, C₄-C₁₂cycloalkylalkyl, aryl, C₇-C₁₂aralkyl, C₃-C₁₂heterocyclyl, C₃-C₁₂heterocyclylalkyl, C₁-C₁₂heteroaryl and C₃-C₁₂heteroarylalkyl;

or R³ is a multi-ring structure having 2 to 4 rings wherein the rings are independently selected from the group consisting of cycloalkyl, heterocyclyl, aryl and heteroaryl and where some or all of the rings may be fused to each other;

R⁴ and R⁵ are each independently selected from hydrogen, fluoro, chloro, methyl, methoxy, trifluoromethyl, cyano, nitro or —N(R¹²)₂;

R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each independently selected from hydrogen or C₁-C₃alkyl;

or R⁶ and R^(6a) together, or R⁷ and R^(7a), together, or R⁸ and R^(8a) together, or R⁹ and R^(9a) together are an oxo group, provided that when V is —C(O)—, R⁷ and R^(7a) together or R⁸ and R^(8a) together do not form an oxo group, while the remaining R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each independently selected from hydrogen or C₁-C₃alkyl;

or one of R⁶, R^(6a), R⁷, and R^(7a) together with one of R⁸, R^(8a), R⁹ and R^(9a) form an alkylene bridge, while the remaining R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each independently selected from hydrogen or C₁-C₃alkyl;

R¹⁰ is hydrogen or C₁-C₃alkyl; and

each R¹² is independently selected from hydrogen or C₁-C₆alkyl;

a stereoisomer, enantiomer or tautomer thereof, a pharmaceutically acceptable salt thereof, a pharmaceutical composition thereof or a prodrug thereof.

In accordance with some embodiments of the invention, a method for treating or preventing skin disorders may preferably use compounds of formula (I):

wherein:

-   -   V is —C(O)—;     -   W is selected from —C(O)N(R¹)— and —N(R¹)C(O)—;     -   R² is selected from the group consisting of C₇-C₁₂alkyl,         C₃-C₁₂alkenyl, C₇-C₁₂hydroxyalkyl, C₂-C₁₂alkoxyalkyl,         C₃-C₁₂hydroxyalkenyl, C₃-C₁₂cycloalkyl, C₄-C₁₂cycloalkylalkyl,         C₃-C₁₉aralkyl, C₃-C₁₂heterocyclylalkyl, and         C₃-C₁₂heteroarylalkyl;     -   R³ is selected from the group consisting of C₃-C₁₂alkyl,         C₃-C₁₂alkenyl, C₃-C₁₂hydroxyalkyl, C₃-C₁₂hydroxyalkenyl,         C₃-C₁₂alkoxy, C₃-C₁₂alkoxyalkyl, C₃-C₁₂cycloalkyl,         C₄-C₁₂cycloalkylalkyl, aryl, C₇-C₁₂aralkyl, C₃-C₁₂heterocyclyl,         C₃-C₁₂heterocyclylalkyl, C₅-C₁₂ heteroaryl and         C₃-C₁₂heteroarylalkyl;     -   R⁴ and R⁵ are each independently selected from hydrogen, fluoro,         chloro, methyl, methoxy and trifluoromethyl; and     -   R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each         independently selected from hydrogen or C₁-C₃alkyl.

In accordance with some embodiments of the invention, a method for treating or preventing skin disorders may preferably use compounds of formula (I):

wherein:

-   -   V is —C(O)— or —C(S)—;     -   W is selected from —C(O)N(R¹)— and —N(R¹)C(O)—;     -   R² is selected from the group consisting of C₁-C₁₂alkyl,         C₂-C₁₂alkenyl, C₂-C₁₂hydroxyalkyl, C₂-C₁₂hydroxyalkenyl,         C₁-C₆alkoxy, C₃-C₁₂alkoxyalkyl, C₃-C₁₂cycloalkyl,         C₄-C₁₂cycloalkylalkyl, aryl, C₇-C₁₂aralkyl, C₃-C₁₂ heterocyclyl,         C₃-C₁₂heterocyclylalkyl, C₁-C₁₂heteroaryl and         C₃-C₁₂heteroarylalkyl;     -   R³ is phenyl optionally substituted by one or more substituents         selected from the group consisting of halo, cyano, nitro,         hydroxy, C₁-C₆alkyl, C₁-C₆trihaloalkyl, C₁-C₆trihaloalkoxy,         C₁-C₆alkylsulfonyl, —N(R¹¹)₂, —OC(O)R¹¹, —C(O)OR¹¹,         —S(O)₂N(R¹¹)₂, cycloalkyl, heterocyclyl, heteroaryl and         heteroarylcycloalkyl, provided that R³ is not phenyl substituted         with optionally substituted thienyl;     -   R⁴ and R⁵ are each independently selected from hydrogen, fluoro,         chloro, methyl, methoxy and trifluoromethyl;     -   R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each         independently selected from hydrogen or C₁-C₃alkyl.

In accordance with some embodiments of the invention, a method for treating or preventing skin disorders may preferably use compounds of formula (I):

wherein:

-   -   V is —C(O)—;     -   W is —N(R¹)C(O)N(R¹)—     -   R² is selected from the group consisting of C₁-C₁₂alkyl,         C₂-C₁₂alkenyl, C₂-C₁₂hydroxyalkyl, C₂-C₁₂hydroxyalkenyl,         C₂-C₁₂alkoxyalkyl, C₃-C₁₂cycloalkyl, C₄-C₁₂cycloalkylalkyl,         C₃-C₁₂heterocyclyl, C₃-C₁₂heterocyclylalkyl, aryl,         C₇-C₁₂aralkyl, C₁-C₁₂heteroaryl, and C₃-C₁₂heteroarylalkyl;     -   R⁴ and R⁵ are each independently selected from hydrogen, fluoro,         chloro, methyl, methoxy and trifluoromethyl; and     -   R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each         independently selected from hydrogen or C₁-C₃alkyl.

In accordance with some embodiments of the invention, a method for treating or preventing skin disorders may preferably use compounds of formula (I):

wherein:

-   -   V is —C(R¹⁰)H     -   W is —C(O)N(R¹)—; —N(R¹)C(O)N(R¹)— or —N(R¹)C(O)—;         -   R² is selected from the group consisting of C₇-C₁₂alkyl,             C₂-C₁₂alkenyl, C₇-C₁₂hydroxyalkyl, C₂-C₁₂hydroxyalkenyl,             C₁-C₁₂alkoxy, C₂-C₁₂alkoxyalkyl, C₃-C₁₂cycloalkyl,             C₄-C₁₂cycloalkylalkyl, C₃-C₁₉aralkyl, C₃-C₁₂heterocyclyl,             C₃-C₁₂heterocyclylalkyl, C₁-C₁₂heteroaryl, and             C₃-C₁₂heteroarylalkyl;         -   R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each             independently selected from hydrogen or C₁-C₃alkyl.

In another aspect, the invention provides methods of preventing or treating skin disorders mediated by SCD, such as acne, rosacea, and seborrheic skin, comprising administering to a subject in need thereof a therapeutically or prophylactically effective amount of a composition as disclosed herein. The present invention also relates to novel compounds having therapeutic ability to reduce the levels of sebum production or the number or the size of sebaceous glands of skin in an animal.

In another aspect, the invention provides pharmaceutical compositions comprising the compounds of the invention as set forth above and one or more pharmaceutically acceptable excipients. In one embodiment, the present invention relates to a pharmaceutical composition comprising a compound of the invention in a pharmaceutically acceptable carrier and a percutaneous penetration enhancer, in an amount effective to modulate the levels of sebum production, or the number or the size of sebaceous glands of skin, or to treat skin diseases such as acne, rosacea, and seborrheic skin, when administered to a mammal, preferably a human.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a schematic of an area of skin with a follicle unit.

FIG. 2A shows a histochemical staining of a section of an un-treated skin (treated with a vehicle), illustrating the number and size of sebaceous glands in a control sample.

FIG. 2B shows a histochemical staining of a section of a skin treated with a compound of the invention, illustrating the reduction in the number and size of sebaceous glands in a treatment sample.

FIG. 3A shows a histochemical staining of a section of an un-treated skin (treated with a vehicle), illustrating the relative abundance of follicle associated lipids.

FIG. 3B shows t histochemical staining of a section of a skin treated with a compound of the invention, illustrating the reduction in the amount of lipids associated with follicle.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

Certain chemical groups named herein are preceded by a shorthand notation indicating the total number of carbon atoms that are to be found in the indicated chemical group. For example; C₇-C₁₂alkyl describes an alkyl group, as defined below, having a total of 7 to 12 carbon atoms, and C₄-C₁₂cycloalkylalkyl describes a cycloalkylalkyl group, as defined below, having a total of 4 to 12 carbon atoms. The total number of carbons in the shorthand notation does not include carbons that may exist in substituents of the group described.

As used in the specification and appended claims, unless specified to the contrary, a substitution has its regular meaning as known to one skilled in the art and the following terms have the meaning indicated:

“Oxo” refers to the ═O substituent.

“Thioxo” refers to the ═S substituent.

“Alkyl” refers to a straight or branched hydrocarbon chain radical consisting solely of carbon and hydrogen atoms, containing no unsaturation, having from one to twelve carbon atoms, preferably one to eight carbon atoms or one to six carbon atoms, and which is attached to the rest of the molecule by a single bond, e.g., methyl, ethyl, n-propyl, 1-methylethyl (iso-propyl), n-butyl, n-pentyl, 1,1-dimethylethyl (t-butyl), and the like. Unless stated otherwise specifically in the specification, an alkyl group may be optionally substituted by one of the following groups: halo, cyano, nitro, —OR¹⁴, —OC(O)—R¹⁴, —N(R¹⁴)₂, —C(O)R¹⁴, —C(O)R¹⁴, —C(O)N(R¹⁴)₂, —N(R¹⁴)C(O)OR¹⁶, —N(R¹⁴)C(O)R¹⁶, —N(R¹⁴)(S(O)_(t)R¹⁶) (where t is 1 to 2), —S(O)_(t)OR¹⁶ (where t is 1 to 2), —S(O)R¹⁶ (where t is 0 to 2), and —S(O)_(t)N(R¹⁴), (where t is 1 to 2) where each R¹⁴ is independently hydrogen, alkyl, haloalkyl, cycloalkyl, cycloalkylalkyl, aryl (optionally substituted with one or more halo groups), aralkyl, heterocyclyl, heterocylylalkyl, heteroaryl or heteroarylalkyl; and each R¹⁶ is alkyl, haloalkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocyclyl, heterocylylalkyl, heteroaryl or heteroarylalkyl, and where each of the above substituents is unsubstituted unless otherwise indicated.

“C₁-C₃alkyl,” “C₁-C₆alkyl,” “C₁-C₁₂alkyl,” “C₂-C₆alkyl,” “C₃-C₆alkyl,” “C₃-C₁₂alkyl,” “C₆-C₁₂alkyl,” or “C₇-C₁₂alkyl,” refers to an alkyl radical containing the number of carbon atoms indicated in the range and may be optionally substituted as defined above.

“Alkenyl” refers to a straight or branched hydrocarbon chain radical group consisting solely of carbon and hydrogen atoms, containing at least one double bond, having from two to twelve carbon atoms, preferably one to eight carbon atoms and which is attached to the rest of the molecule by a single bond, e.g., ethenyl, prop-1-enyl, but-1-enyl, pent-1-enyl, penta-1,4-dienyl, and the like. Unless stated otherwise specifically in the specification, an alkenyl group may be optionally substituted by one of the following groups: halo, cyano, nitro, —OR¹⁴, —OC(O)—R¹⁴, —N(R¹⁴)₂, —C(O)R¹⁴, —C(O)OR¹⁴, —C(O)N(R¹⁴)₂, —N(R¹⁴)C(O)OR¹⁶, —N(R¹⁴)C(O)R¹⁶, —N(R¹⁴)(S(O)_(t)N(R¹⁴) (where t is 1 to 2), —S(O)_(t)OR¹⁶ (where t is 1 to 2), —S(O)_(t)R¹⁶ (where t is 0 to 2), and —S(O)_(t)N(R¹⁴)₂ (where t is 1 to 2) where each R¹⁴ is independently hydrogen, alkyl, haloalkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocyclyl, heterocylylalkyl, heteroaryl or heteroarylalkyl; and each R¹⁶ is alkyl, haloalkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocyclyl, heterocyclylalkyl, heteroaryl or heteroarylalkyl, and where each of the above substituents is unsubstituted.

“C₃-C₁₂alkenyl” refers to an alkenyl radical as defined above containing three to 12 carbon atoms. The C₃-C₁₂alkenyl radical may be optionally substituted as defined for an alkenyl group.

“C₂-C₁₂alkenyl” refers to an alkenyl radical as defined above containing two to 12 carbon atoms. The C₂-C₁₂alkenyl radical may be optionally substituted as defined above for an alkenyl group.

“Alkylene” and “alkylene chain” refer to a straight or branched divalent hydrocarbon chain, linking the rest of the molecule to a radical group, consisting solely of carbon and hydrogen, containing no unsaturation and having from one to twelve carbon atoms, preferably having from one to eight carbons, e.g., methylene, ethylene, propylene n-butylene, and the like. The alkylene chain may be attached to the rest of the molecule and to the radical group through one carbon within the chain or through any two carbons within the chain.

“Alkenylene” and “alkenylene chain” refer to a straight or branched divalent hydrocarbon chain linking the rest of the molecule to a radical group, consisting solely of carbon and hydrogen, containing at least one double bond and having from two to twelve carbon atoms, e.g., ethenylene, propenylene, n-butenylene, and the like. The alkenylene chain is attached to the rest of the molecule through a single bond and to the radical group through a double bond or a single bond. The points of attachment of the alkenylene chain to the rest of the molecule and to the radical group can be through one carbon or any two carbons within the chain.

“Alkylene bridge” refers to a straight or branched divalent hydrocarbon bridge, linking two different carbons of the same ring structure, consisting solely of carbon and hydrogen, containing no unsaturation and having from one to twelve carbon atoms, preferably having from one to eight carbons, e.g., methylene, ethylene, propylene, n-butylene, and the like. The alkylene bridge may link any two carbons within the ring structure.

“Alkoxy” refers to a radical of the formula —OR_(a) where R_(a) is an alkyl radical as defined above. The alkyl part of the alkoxy radical may be optionally substituted as defined above for an alkyl radical.

“C₁-C₆alkoxy” refers to an alkoxy radical as defined above containing one to six carbon atoms. The alkyl part of the C₁-C₆alkoxy radical may be optionally substituted as defined above for an alkyl group.

“C₁-C₁₂alkoxy” refers to an alkoxy radical as defined above containing one to twelve carbon atoms. The alkyl part of the C₁-C₁₂alkoxy radical may be optionally substituted as defined above for an alkyl group.

“C₃-C₁₂alkoxy” refers to an alkoxy radical as defined above containing three to twelve carbon atoms. The alkyl part of the C₃-C₁₂alkoxy radical may be optionally substituted as defined above for an alkyl group.

“Alkoxyalkyl” refers to a radical of the formula —R^(a)—O—R_(a) where each R_(a) is independently an alkyl radical as defined above. The oxygen atom may be bonded to any carbon in either alkyl radical. Each alkyl part of the alkoxyalkyl radical may be optionally substituted as defined above for an alkyl group.

“C₂-C₁₂alkoxyalkyl” refers to an alkoxyalkyl radical as defined above containing two to twelve carbon atoms. Each alkyl part of the C₂-C₁₂alkoxyalkyl radical may be optionally substituted as defined above for an alkyl group.

“C₃alkoxyalkyl” refers to an alkoxyalkyl radical as defined above containing three carbon atoms. Each alkyl part of the C₃alkoxyalkyl radical may be optionally substituted as defined above for an alkyl group.

“C₃-C₁₂alkoxyalkyl” refers to an alkoxyalkyl radical as defined above containing three to twelve carbon atoms. Each alkyl part of the C₃-C₁₂alkoxyalkyl radical may be optionally substituted as defined above for an alkyl group.

“Alkylsulfonyl” refers to a radical of the formula —S(O)₂R_(a), where R_(a) is an alkyl group as defined above. The alkyl part of the alkylsulfonyl radical may be optionally substituted as defined above for an alkyl group.

“C₁-C₆alkylsulfonyl” refers to an alkylsulfonyl radical as defined above having one to six carbon atoms. The C₁-C₆alkylsulfonyl group may be optionally substituted as defined above for an alkylsulfonyl group.

“Aryl” refers to aromatic monocyclic or multicyclic hydrocarbon ring system consisting only of hydrogen and carbon and containing from 6 to 19 carbon atoms, preferably 6 to 10 carbon atoms, where the ring system may be partially or fully saturated. Aryl groups include, but are not limited to groups such as fluorenyl, phenyl and naphthyl. Unless stated otherwise specifically in the specification, the term “aryl” or the prefix “ar-” (such as in “aralkyl”) is meant to include aryl radicals optionally substituted by one or more substituents selected from the group consisting of halo, cyano, nitro, —R¹⁵—OR¹⁴, —R¹⁵—OC(O)—R¹⁴, —R¹⁵—N(R¹⁴)₂, —R¹⁵—C(O)R¹⁴, —R¹⁵—C(O)OR¹⁴, —R¹⁵—C(O)N(R¹⁴)₂, —R¹⁵—N(R¹⁴)C(O)OR¹⁶, —R¹⁵—N(R¹⁴)C(O)R¹⁶, —R¹⁵—N(R¹⁴)(S(O)_(t)R¹⁶) (where t is 1 to 2), —R¹⁵—S(O)_(t)OR¹⁶ (where t is 1 to 2), —R¹⁵—S(O)_(t)R¹⁶ (where t is 0 to 2), and —R¹⁵ (—S(O)N(R¹⁴)₂ (where t is 1 to 2) where each R¹⁴ is independently hydrogen, alkyl, haloalkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocyclyl, heterocyclylalkyl, heteroaryl or heteroarylalkyl; each R¹⁵ is independently a direct bond or a straight or branched alkylene or alkenylene chain; and each R¹⁶ is alkyl, haloalkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocyclyl, heterocyclylalkyl, heteroaryl or heteroarylalkyl, and where each of the above substituents is unsubstituted.

“Aralkyl” refers to a radical of the formula —R_(a)R_(b) where R_(a) is an alkyl radical as defined above and R_(b) is one or more aryl radicals as defined above e.g., benzyl, diphenylmethyl and the like. The aryl part of the aralkyl radical may be optionally substituted as described above for an aryl group. The alkyl part of the aralkyl radical may be optionally substituted as defined above for an alkyl group.

“C₇-C₁₂aralkyl” refers to an aralkyl group as defined above containing seven to twelve carbon atoms. The aryl part of the C₇-C₁₂aralkyl radical may be optionally substituted as described above for an aryl group. The alkyl part of the C₇-C₁₂aralkyl radical may be optionally substituted as defined above for an alkyl group.

“C₁₃-C₁₉aralkyl” refers to an aralkyl group as defined above containing thirteen to nineteen carbon atoms. The aryl part of the C₁₃-C₁₉aralkyl radical may be optionally substituted as described above for an aryl group. The alkyl part of the C₁₃-C₁₉aralkyl radical may be optionally substituted as defined above for an alkyl group.

“Aralkenyl” refers to a radical of the formula —R_(c)R_(b) where R_(c) is an alkenyl radical as defined above and R_(b) is one or more aryl radicals as defined above, which may be optionally substituted as described above. The aryl part of the aralkenyl radical may be optionally substituted as described above for an aryl group. The alkenyl part of the aralkenyl radical may be optionally substituted as defined above for an alkenyl group.

“Aryloxy” refers to a radical of the formula —OR_(b) where R_(b) is an aryl group as defined above. The aryl part of the aryloxy radical may be optionally substituted as defined above.

“Aryl-C₁-C₆alkyl” refers to a radical of the formula —R_(h)-R_(i) where R_(h) is an unbranched alkyl radical having one to six carbons and R_(h) is an aryl group attached to the terminal carbon of the alkyl radical.

“Cycloalkyl” refers to a stable non-aromatic monocyclic or bicyclic hydrocarbon radical consisting solely of carbon and hydrogen atoms, having from three to fifteen carbon atoms, preferably having from three to twelve carbon atoms, and which is saturated or unsaturated and attached to the rest of the molecule by a single bond, e.g., cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, decalinyl and the like. Unless otherwise stated specifically in the specification, the term “cycloalkyl” is meant to include cycloalkyl radicals which are optionally substituted by one or more substituents selected from the group consisting of halo, cyano, nitro, —R¹⁵—OR¹⁴, —R¹⁵—OC(O)—R¹⁴, —R¹⁵—N(R¹⁴)₂, —R¹⁵—C(O)R¹⁴, —R¹⁵—C(O)OR¹⁴, —R¹⁵—C(O)N(R¹⁴)₂, —R¹⁵—N(R¹⁴)C(O)OR¹⁶, —R¹⁵—N(R¹⁴)C(O)R¹⁶, —R¹⁵—N(R¹⁴)(S(O)_(t)R¹⁶) (where t is 1 to 2), —R¹⁵—S(O)_(t)OR¹⁶ (where t is 1 to 2), —R¹⁵—S(O)_(t)R¹⁶ (where t is 0 to 2), and —R¹⁵—S(O)_(t)N(R¹⁴)₂ (where t is 1 to 2) where each R¹⁴ is independently hydrogen, alkyl, haloalkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocyclyl, heterocyclylalkyl, heteroaryl or heteroarylalkyl; each R¹⁵ is independently a direct bond or a straight or branched alkylene or alkenylene chain; and each R¹⁶ is alkyl, haloalkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocyclyl, heterocyclylalkyl, heteroaryl or heteroarylalkyl, and where each of the above substituents is unsubstituted.

“C₃-C₆cycloalkyl” refers to a cycloalkyl radical as defined above having three to six carbon atoms. The C₃-C₆cycloalkyl radical may be optionally substituted as defined above for a cycloalkyl group.

“C₃-C₁₂cycloalkyl” refers to a cycloalkyl radical as defined above having three to twelve carbon atoms. The C₃-C₁₂cycloalkyl radical may be optionally substituted as defined above for a cycloalkyl group.

“Cycloalkylalkyl” refers to a radical of the formula —R_(a)R_(d) where R_(a) is an alkyl radical as defined above and R_(d) is a cycloalkyl radical as defined above. The cycloalkyl part of the cycloalkyl radical may be optionally substituted as defined above for an cycloalkyl radical. The alkyl part of the cycloalkyl radical may be optionally substituted as defined above for an alkyl radical.

“C₄-C₁₂cycloalkylalkyl” refers to a cycloalkylalkyl radical as defined above having four to twelve carbon atoms. The C₄-C₁₂cycloalkylalkyl radical may be optionally substituted as defined above for a cycloalkylalkyl group.

“Halo” refers to bromo, chloro, fluoro or iodo.

“Haloalkyl” refers to an alkyl radical, as defined above, that is substituted by one or more halo radicals, as defined above, e.g., trifluoromethyl, difluoromethyl, trichloromethyl, 2,2,2-trifluoroethyl, 1-fluoromethyl-2-fluoroethyl, 3-bromo-2-fluoropropyl, 1-bromomethyl-2-bromoethyl, and the like. The alkyl part of the haloalkyl radical may be optionally substituted as defined above for an alkyl group.

“Haloalkenyl” refers to an alkenyl radical, as defined above, that is substituted by one or more halo radicals, as defined above, e.g., 2-bromoethenyl, 3-bromoprop-1-enyl, and the like. The alkenyl part of the haloalkenyl radical may be optionally substituted as defined above for an alkyl group.

“Heterocyclyl” refers to a stable 3- to 18-membered non-aromatic ring radical which consists of carbon atoms and from one to five heteroatoms selected from the group consisting of nitrogen, oxygen and sulfur. For purposes of this invention, the heterocyclyl radical may be a monocyclic, bicyclic, tricyclic or tetracyclic ring system, which may include fused or bridged ring systems; and the nitrogen, carbon or sulfur atoms in the heterocyclyl radical may be optionally oxidized; the nitrogen atom may be optionally quaternized; and the heterocyclyl radical may be partially or fully saturated. Examples of such heterocyclyl radicals include, but are not limited to, dioxolanyl, decahydroisoquinolyl, imidazolinyl, imidazolidinyl, isothiazolidinyl, isoxazolidinyl, morpholinyl, octahydroindolyl, octahydroisoindolyl, 2-oxopiperazinyl, 2-oxopiperidinyl, 2-oxopyrrolidinyl, oxazolidinyl, piperidinyl, piperazinyl, 4-piperidonyl, pyrrolidinyl, pyrazolidinyl, thiazolidinyl, tetrahydrofuryl, trithianyl, tetrahydropyranyl, thiomorpholinyl, thiamorpholinyl, 1-oxo-thiomorpholinyl, and 1,1-dioxo-thiomorpholinyl. Unless stated otherwise specifically in the specification, the term “heterocyclyl” is meant to include heterocyclyl radicals as defined above which are optionally substituted by one or more substituents selected from the group consisting of halo, cyano, oxo, thioxo, nitro, —R¹⁵—OR¹⁴, —R¹⁵—OC(O)—R¹⁴, —R¹⁵—N(R¹⁴), —R¹⁵—C(O)R¹⁴, —R¹⁵—C(O)OR¹⁴, —R¹⁵—C(O)N(R¹⁴)₂, —R¹⁵—N(R¹⁴)C(O)OR¹⁶, —R¹⁵—N(R¹⁴)C(O)R¹⁶, —R¹⁵—N(R¹⁴)(S(O)_(t)R¹⁶) (where t is 1 to 2), —R¹⁵—S(O)_(t)OR¹⁶ (where t is 1 to 2), —R¹⁵—S(O)_(t)R¹⁶ (where t is 0 to 2), and —R¹⁵—S(O)_(t)N(R¹⁴)₂ (where t is 1 to 2) where each R¹⁴ is independently hydrogen, alkyl, alkenyl, haloalkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocyclyl, heterocyclylalkyl, heteroaryl or heteroarylalkyl; each R¹⁵ is independently a direct bond or a straight or branched alkylene or alkenylene chain; and each R¹⁶ is alkyl, alkenyl, haloalkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocyclyl, heterocyclylalkyl, heteroaryl or heteroarylalkyl, and where each of the above substituents is unsubstituted.

“C₃-C₁₂heterocyclyl” refers to a heterocyclyl radical as defined above having three to twelve carbons. The C₃-C₁₂heterocyclyl may be optionally substituted as defined above for a heterocyclyl group.

“Heterocyclylalkyl” refers to a radical of the formula —R_(a)R_(e) where R_(a) is an alkyl radical as defined above and R_(e) is a heterocyclyl radical as defined above, and if the heterocyclyl is a nitrogen-containing heterocyclyl, the heterocyclyl may be attached to the alkyl radical at the nitrogen atom. The alkyl part of the heterocyclylalkyl radical may be optionally substituted as defined above for an alkyl group. The heterocyclyl part of the heterocyclylalkyl radical may be optionally substituted as defined above for a heterocyclyl group.

“C₃-C₂heterocyclylalkyl” refers to a heterocyclylalkyl radical as defined above having three to twelve carbons. The C₃-C₂heterocyclylalkyl radical may be optionally substituted as defined above for a heterocyclylalkyl group.

“Heteroaryl” refers to a 5- to 18-membered aromatic ring radical which consists of carbon atoms and from one to five heteroatoms selected from the group consisting of nitrogen, oxygen and sulfur. For purposes of this invention, the heteroaryl radical may be a monocyclic, bicyclic, tricyclic or tetracyclic ring system, which may include fused or bridged ring systems; and the nitrogen, carbon or sulfur atoms in the heteroaryl radical may be optionally oxidized; the nitrogen atom may be optionally quaternized. Examples include, but are not limited to, azepinyl, acridinyl, benzimidazolyl, benzthiazolyl, benzindolyl, benzothiadiazolyl, benzonaphthofuranyl, benzoxazolyl, benzodioxolyl, benzodioxinyl, benzopyranyl, benzopyranonyl, benzofuranyl, benzofuranonyl, benzothienyl (benzothiophenyl), benzotriazolyl, benzo[4,6]imidazo[1,2-a]pyridinyl, carbazolyl, cinnolinyl, dibenzofuranyl, furanyl, furanonyl, isothiazolyl, imidazolyl, indolyl, indazolyl, isoindolyl, indolinyl, isoindolinyl, indolizinyl, isoxazolyl, naphthyridinyl, oxadiazolyl, 2-oxoazepinyl, oxazolyl, oxiranyl, phenazinyl, phenothiazinyl, phenoxazinyl, phthalazinyl, pteridinyl, purinyl, pyrrolyl, pyrazolyl, pyridinyl, pyrazinyl, pyrimidinyl, pyridazinyl, quinazolinyl, quinoxalinyl, quinolinyl, quinuclidinyl, isoquinolinyl, thiazolyl, thiadiazolyl, triazolyl, tetrazolyl, triazinyl, and thiophenyl. Unless stated otherwise specifically in the specification, the term “heteroaryl” is meant to include heteroaryl radicals as defined above which are optionally substituted by one or more substituents selected from the group consisting of halo, cyano, oxo, thioxo, nitro, —R¹⁵—OR¹⁴, —R¹⁵—OC(O)—R¹⁴, —R¹⁵—N(R¹⁴)₂, —R¹⁵—C(O)R¹⁴, —R¹⁵—C(O)OR¹⁴, —R¹⁵—C(O)N(R¹⁴)₂, —R¹⁵—N(R¹⁴)C(O)OR¹⁶, —R¹⁵—N(R¹⁴)C(O)R¹⁶, —R¹⁵—N(R¹⁴)(S(O)_(t)R¹⁶) (where t is 1 to 2), —R¹⁵—S(O)_(t)OR¹⁶ (where t is 1 to 2), —R¹⁵—S(O)_(t)R¹⁶ (where t is 0 to 2), and —R¹⁵—S(O)N(R¹⁴)₂ (where t is 1 to 2) where each R¹⁴ is independently hydrogen, alkyl, alkenyl, haloalkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocyclyl, heterocyclylalkyl, heteroaryl or heteroarylalkyl; each R¹⁵ is independently a direct bond or a straight or branched alkylene or alkenylene chain; and each R¹⁶ is alkyl, alkenyl, haloalkyl, cycloalkyl, cycloalkylalkyl, aryl, aralkyl, heterocyclyl, heterocyclylalkyl, heteroaryl or heteroarylalkyl, and where each of the above substituents is unsubstituted.

“C₁-C₁₂heteroaryl” refers to a heteroaryl radical as defined above having one to twelve carbon atoms. The C₁-C₁₂heteroaryl group may be optionally substituted as defined above for a heteroaryl group.

“C₅-C₁₂heteroaryl” refers to a heteroaryl radical as defined above having five to twelve carbon atoms. The C₅-C₁₂heteroaryl group may be optionally substituted as defined above for a heteroaryl group.

“Heteroarylalkyl” refers to a radical of the formula —R_(a)R_(f) where R_(a) is an alkyl radical as defined above and R_(f) is a heteroaryl radical as defined above. The heteroaryl part of the heteroarylalkyl radical may be optionally substituted as defined above for a heteroaryl group. The alkyl part of the heteroarylalkyl radical may be optionally substituted as defined above for an alkyl group.

“C₃-C₁₂heteroarylalkyl” refers to a heteroarylalkyl radical as defined above having three to twelve carbon atoms. The C₃-C₁₂heteroarylalkyl group may be optionally substituted as defined above for a heteroarylalkyl group.

“Heteroarylcycloalkyl” refers to a radical of the formula —R_(d)R_(f) where R_(d) is a cycloalkyl radical as defined above and R_(f) is a heteroaryl radical as defined above. The cycloalkyl part of the heteroarylcycloalkyl radical may be optionally substituted as defined above for a cycloalkyl group. The heteroaryl part of the heteroarylcycloalkyl radical may be optionally substituted as defined above for a heteroaryl group.

“Heteroarylalkenyl” refers to a radical of the formula —R_(b)R_(f) where R_(b) is an alkenyl radical as defined above and R_(f) is a heteroaryl radical as defined above. The heteroaryl part of the heteroarylalkenyl radical may be optionally substituted as defined above for a heteroaryl group. The alkenyl part of the heteroarylalkenyl radical may be optionally substituted as defined above for an alkenyl group.

“Hydroxyalkyl” refers to a radical of the formula —R_(a)—OH where R_(a) is an alkyl radical as defined above. The hydroxy group may be attached to the alkyl radical on any carbon within the alkyl radical. The alkyl part of the hydroxyalkyl group may be optionally substituted as defined above for an alkyl group.

“C₂-C₁₂hydroxyalkyl” refers to a hydroxyalkyl radical as defined above containing two to twelve carbon atoms. The alkyl part of the C₂-C₁₂hydroxyalkyl radical may be optionally substituted as defined above for an alkyl group.

“C₃-C₁₂hydroxyalkyl” refers to an hydroxyalkyl radical as defined above containing three to twelve carbon atoms. The alkyl part of the C₃-C₁₂hydroxyalkyl radical may be optionally substituted as defined above for an alkyl group.

“C₇-C₁₂hydroxyalkyl” refers to a hydroxyalkyl radical as defined above containing seven to twelve carbon atoms. The alkyl part of the C₇-C₁₂hydroxyalkyl radical may be optionally substituted as defined above for an alkyl group.

“Hydroxyalkenyl” refers to a radical of the formula —R_(c)—OH where R_(c) is an alkenyl radical as defined above. The hydroxy group may be attached to the alkenyl radical on any carbon within the alkenyl radical. The alkenyl part of the hydroxyalkenyl group may be optionally substituted as defined above for an alkenyl group.

“C₂-C₁₂hydroxyalkenyl” refers to a hydroxyalkenyl radical as defined above containing two to twelve carbon atoms. The alkenyl part of the C₂-C₁₂hydroxyalkenyl radical may be optionally substituted as defined above for an alkenyl group.

“C₃-C₁₂hydroxyalkenyl” refers to an hydroxyalkenyl radical as defined above containing three to twelve carbon atoms. The alkenyl part of the C₃-C₁₂hydroxyalkenyl radical may be optionally substituted as defined above for an alkenyl group.

“Hydroxyl-C₁-C₆-alkyl” refers to a radical of the formula —R_(h)—OH where R_(h) is an unbranched alkyl radical having one to six carbons and the hydroxy radical is attached to the terminal carbon.

“Trihaloalkyl” refers to an alkyl radical, as defined above, that is substituted by three halo radicals, as defined above, e.g., trifluoromethyl. The alkyl part of the trihaloalkyl radical may be optionally substituted as defined above for an alkyl group.

“C₁-C₆trihaloalkyl” refers to a trihaloalkyl radical as defined above having one to six carbon atoms. The C₁-C₆trihaloalkyl may be optionally substituted as defined above for a trihaloalkyl group.

“Trihaloalkoxy” refers to a radical of the formula —OR_(g) where R_(g) is a trihaloalkyl group as defined above. The trihaloalkyl part of the trihaloalkoxy group may be optionally substituted as defined above for a trihaloalkyl group.

“C₁-C₆-trihaloalkoxy” refers to a trihaloalkoxy radical as defined above having one to six carbon atoms. The C₁-C₆trihaloalkoxy group may be optionally substituted as defined above for a trihaloalkoxy group.

“A multi-ring structure” refers to a multicyclic ring system comprised of two to four rings wherein the rings are independently selected from cycloalkyl, aryl, heterocyclyl or heteroaryl as defined above. Each cycloalkyl may be optionally substituted as defined above for a cycloalkyl group. Each aryl may be optionally substituted as defined above for an aryl group. Each heterocyclyl may be optionally substituted as defined above for a heterocyclyl group. Each heteroaryl may be optionally substituted as defined above for a heteroaryl group. The rings may be attached to other through direct bonds or some or all of the rings may be fused to each other. Examples include, but are not limited to a cycloalkyl radical substituted by aryl group; a cycloalkyl group substituted by an aryl group, which, in turn, is substituted by another aryl group; and so forth.

“Stable compound” and “stable structure” are meant to indicate a compound that is sufficiently robust to survive isolation to a useful degree of purity from a reaction mixture, and formulation into an efficacious therapeutic agent.

“Mammal” includes humans and domestic animals, such as cats, dogs, swine, cattle, sheep, goats, horses, rabbits, and the like.

“Optional” or “optionally”; means that the subsequently described event of circumstances may or may not occur, and that the description includes instances where said event or circumstance occurs and instances in which it does not. For example, “optionally substituted aryl” means that the aryl radical may or may not be substituted and that the description includes both substituted aryl radicals and aryl radicals having no substitution.

“Pharmaceutically acceptable carrier, diluent or excipient” includes without limitation any adjuvant, carrier, excipient, glidant, sweetening agent, diluent, preservative, dye/colorant, flavor enhancer, surfactant, wetting agent, dispersing agent, suspending agent, stabilizer, isotonic agent, solvent, or emulsifier which has been approved by the United States Food and Drug Administration as being acceptable for use in humans or domestic animals.

“Pharmaceutically acceptable salt” includes both acid and base addition salts.

“Pharmaceutically acceptable acid addition salt” refers to those salts which retain the biological effectiveness and properties of the free bases, which are not biologically or otherwise undesirable, and which are formed with inorganic acids such as, but not limited to, hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid and the like, and organic acids such as, but not limited to, acetic acid, 2,2-dichloroacetic acid, adipic acid, alginic acid, ascorbic acid, aspartic acid, benzenesulfonic acid, benzoic acid, 4-acetaroidobenzoic acid, camphoric acid, camphor-10-sulfonic acid, capric acid, caproic acid, caprylic acid, carbonic acid, cinnamic acid, citric acid, cyclamic acid, dodecylsulfuric acid, ethane-1,2-disulfonic acid, ethanesulfonic acid, 2-hydroxyethanesulfonic acid, formic acid, fumaric acid, galactaric acid, gentisic acid, glucoheptonic acid, gluconic acid, glucuronic acid, glutamic acid, glutaric acid, 2-oxo-glutaric acid, glycerophosphoric acid, glycolic acid, hippuric acid, isobutyric acid, lactic acid, lactobionic acid, lauric acid, maleic acid, malic acid, malonic acid, mandelic acid, methanesulfonic acid, mucic acid, naphthalene-1,5-disulfonic acid, naphthalene-2-sulfonic acid, 1-hydroxy-2-naphthoic acid, nicotinic acid, oleic acid, orotic acid, oxalic acid, palinitic acid, pamoic acid, propionic acid, pyroglutamic acid, pyruvic acid, salicylic acid, 4-aminosalicylic acid, sebacic acid, stearic acid, succinic acid, tartaric acid, thiocyanic acid, p-toluenesulfonic acid, trifluoroacetic acid, undecylenic acid, and the like.

“Pharmaceutically acceptable base addition salt” refers to those salts which retain the biological effectiveness and properties of the free acids, which are not biologically or otherwise undesirable. These salts are prepared from addition of an inorganic base or an organic base to the free acid. Salts derived from inorganic bases include, but are not limited to, the sodium, potassium, lithium, ammonium, calcium, magnesium, iron, zinc, copper, manganese, aluminum salts and the like. Preferred inorganic salts are the ammonium, sodium, potassium, calcium, and magnesium salts. Salts derived from organic bases include, but are not limited to, salts of primary, secondary, and tertiary amines, substituted amines including naturally occurring substituted amines, cyclic amines and basic ion exchange resins, such as ammonia, isopropylamine, trimethylamine, diethylamine, triethylamine, tripropylamine, diethanolamine, ethanolamine, deanol, 2-dimethylaminoethanol, 2-diethylaminoethanol, dicyclohexylamine, lysine, arginin-e, histidine, caffeine, procaine, hydrabamine, choline, betaine, benethamine, benzathine, ethylenediamine, glucosamine, methylglucamine, theobromine, triethanolamine, tromethamine, purines, piperazine, piperidine, N-ethylpiperidine, polyamine resins and the like. Particularly preferred organic bases are isopropylamine, diethylamine, ethanolamine, trimethylamine, dicyclohexylamine, choline and caffeine.

Often crystallizations produce a solvate of the compound of the invention. As used herein, the term “solvate” refers to an aggregate that comprises one or more molecules of a compound of the invention with one or more molecules of solvent. The solvent may be water, in which case the solvate may be a hydrate. Alternatively, the solvent may be an organic solvent. Thus, the compounds of the present invention may exist as a hydrate, including a monohydrate, dihydrate, hemihydrate, sesquihydrate, trihydrate, tetrahydrate and the like, as well as the corresponding solvated forms. The compound of the invention may be true solvates, while in other cases, the compound of the invention may merely retain adventitious water or be a mixture of water plus some adventitious solvent.

A “pharmaceutical composition” refers to a formulation of a compound of the invention and a medium generally accepted in the art for the delivery of the biologically active compound to mammals, e.g., humans. Such a medium includes all pharmaceutically acceptable carriers, diluents or excipients therefor.

“Therapeutically effective amount” refers to that amount of a compound of the invention which, when administered to a mammal, preferably a human, is sufficient to effect treatment, as defined below, of an SCD-mediated disease or condition in the mammal, preferably a human. The amount of a compound of the invention which constitutes a “therapeutically effective amount” will vary depending on the compound, the formulations and routes of administration, the condition and severity of the disorder, and the age of the mammal to be treated, but can be determined routinely by one of ordinary skill in the art having regard to his own knowledge and to this disclosure.

“Treating” or “treatment” as used herein covers the treatment of the disease or condition of interest in a mammal, preferably a human, having the disease or disorder of interest, and includes:

(i) preventing the disease or condition from occurring in a mammal, in particular, when such mammal is predisposed to the condition but has not yet been diagnosed as having it;

(ii) inhibiting the disease or condition, i.e., arresting its development; or

(iii) relieving the disease or condition, i.e., causing regression of the disease or condition.

As used herein, the terms “disease” and “condition” may be used interchangeably or may be different in that the particular malady or condition may not have a known causative agent (so that etiology has not yet been worked out) and it is therefore not yet recognized as a disease but only as an undesirable condition or syndrome, wherein a more or less specific set of symptoms have been identified by clinicians.

The compounds of the invention, or their pharmaceutically acceptable salts may contain one or more asymmetric centers and may thus give rise to enantiomers, diastereomers, and other stereoisomeric forms that may be defined, in terms of absolute stereochemistry, as (R)- or (S)- or, as (D)- or (L)- for amino acids. The present invention is meant to include all such possible isomers, as well as their racemic and optically pure forms. Optically active (+) and (−), (R)- and (S)-, or (D)- and (L)-isomers may be prepared using chiral synthons or chiral reagents, or resolved using conventional techniques, such as HPLC using a chiral column. When the compounds described herein contain olefinic double bonds or other centers of geometric asymmetry, and unless specified otherwise, it is intended that the compounds include both E and Z geometric isomers. Likewise, all tautomeric forms are also intended to be included.

A “stereoisomer” refers to a compound made up of the same atoms bonded by the same bonds but having different three-dimensional structures, which are not interchangeable. The present invention contemplates various stereoisomers and mixtures thereof and includes “enantiomers”, which refers to two stereoisomers whose molecules are nonsuperimposeable mirror images of one another.

A “tautomer” refers to a proton shift from one atom of a molecule to another atom of the same molecule. The present invention includes tautomers of any said compounds.

The chemical naming protocol and structure diagrams used herein employ and rely on the chemical naming features as utilized by Chemdraw version 7.0.1 (available from Cambridgesoft Corp., Cambridge, Mass.). For complex chemical names employed herein, a substituent group is named before the group to which it attaches. For example, cyclopropylethyl comprises an ethyl backbone with cyclopropyl substituent. In chemical structure diagrams, all bonds are identified, except for some carbon atoms which are assumed to be bonded to sufficient hydrogen atoms to complete the valency.

For example, a compound of formula (I), as set forth above in the Summary of the Invention, where x and y are both 1; V is —C(O)—; W is —N(R¹)C(O)—; R¹, R⁴, R⁵, R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each hydrogen; R² is 2-cyclopropylethyl and R³ is 2,5-dichlorophenyl, i.e., a compound of the following formula.

is named herein as 6-[4-(2,5-Dichlorobenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid

(2-cyclopropylethyl)amide.

Certain radical groups of the compounds of the invention are depicted herein as linkages between two parts of the compounds of the invention. For example, in the following formula (I):

W is described, for example, as being —N(R¹)C(O)—, —C(O)N(R¹)—, or —N(R¹)C(O)N(R¹)—; and V is described as —C(O)—, —C(S)— or —C(R¹⁰)—. This description is meant to describe a W group attached to the R² group as follows: R²—N(R¹)C(O)—, R²—C(O)N(R¹)—, or R²—N(R¹)C(O)N(R¹)—; and meant to describe a V group attached to the R³ group as follows: —C(O)—R³, —C(R¹⁰)—R³, or —C(S)—R³. In other words, the description of the W and V linkage groups are meant to be read from left to right in view of formula (I) as depicted above.

Embodiments of the Invention

In one embodiment of the invention as set forth above in the Summary of the Invention, a group of compounds of formula (I) is directed to compounds wherein x and y are each 1; V is —C(O)—; W is selected from —C(O)N(R¹)— and —N(R¹)C(O)—; each R¹ is independently selected from hydrogen or C₁-C₆alkyl; R² is selected from the group consisting of C₇-C₁₂alkyl, C₃-C₁₂alkenyl, C₇-C₁₂hydroxyalkyl, C₂-C₁₂alkoxyalkyl, C₃-C₁₂hydroxyalkenyl, C₃-C₁₂cycloalkyl, C₄-C₁₂cycloalkylalkyl, C₃-C₁₉aralkyl, C₃-C₁₂heterocyclylalkyl, and C₃-C₁₂heteroarylalkyl; each R² is optionally substituted by one or more substituents selected from the group consisting of halo, C₁-C₃alkyl, —OR¹¹, —C(O)OR¹¹, C₁-C₆trihaloalkyl, cycloalkyl, heterocyclyl, aryl, heteroaryl and heteroarylcycloalkyl; R³ is selected from the group consisting of C₃-C₁₂alkyl, C₃-C₁₂alkenyl, C₃-C₁₂hydroxyalkyl, C₃-C₁₂hydroxyalkenyl, C₃-C₁₂alkoxy, C₃-C₁₂alkoxyalkyl, C₃-C₁₂cycloalkyl, C₄-C₁₂cycloalkylalkyl, C₇-C₁₂aralkyl, C₃-C₁₂heterocyclyl, C₃-C₁₂heterocyclylalkyl, C₅-C₁₂ heteroaryl and C₃-C₁₂heteroarylalkyl; each R³ is optionally substituted by one or more substituents selected from the group consisting of C₁-C₆alkyl, C₁-C₆trihaloalkyl, C₁-C₆trihaloalkoxy, C₁-C₆alkoxy, C₁-C₆alkylsulfonyl, halo, cyano, nitro, hydroxy, —N(R¹²)₂, —C(O)OR¹¹, —S(O)₂N(R¹²)₂, cycloalkyl, heterocyclyl, aryl, aralkyl, heteroaryl and heteroarylcycloalkyl; R⁴ and R⁵ are each independently selected from hydrogen, fluoro, chloro, methyl, methoxy and trifluoromethyl; and R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each independently selected from hydrogen or C₁-C₃alkyl; each R¹¹ is independently selected from hydrogen, C₁-C₆alkyl, aryl or aralkyl; and each R¹² is independently selected from hydrogen or C₁-C₆alkyl.

Of this group of compounds of formula (I), a subgroup of compounds is directed to compounds wherein V is —C(O)—; W is —N(R¹)C(O)—; R¹ is hydrogen; R² is C₄-C₁₂cycloalkylalkyl; R³ is C₃-C₁₂alkyl or C₃-C₁₂alkenyl, each optionally substituted with one or more halo groups; R⁴ and R⁵ are each hydrogen; and R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each hydrogen.

Another subgroup of this group of compounds of formula (I) is directed to compounds wherein V is —C(O)—; W is —N(R¹)C(O)—; R¹ is hydrogen; R² is C₄-C₁₂cycloalkylalkyl; R³ is C₃-C₁₂cycloalkyl optionally substituted with one or more substituents selected from hydroxy, C₁-C₆trihaloalkyl or C₁-C₆alkyl; R⁴ and R⁵ are each hydrogen; and R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each hydrogen.

Another subgroup of this group of compounds of formula (I) is directed to compounds wherein V is —C(O)—; W is —N(R¹)C(O)—; R² is C₄-C₁₂cycloalkylalkyl and R³ is C₃-C₁₂hydroxyalkyl optionally substituted with one or more halo groups; R⁴ and R⁵ are each hydrogen; and R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each hydrogen.

Another subgroup of this group of compounds of formula (II) is directed to compounds wherein W is —N(R¹)C(O)—; R¹ is hydrogen; R² is C₄-C₁₂cycloalkylalkyl; R³ is C₃-C₁₂alkoxy; R⁴ and R⁵ are each hydrogen; and R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each hydrogen.

Another subgroup of this group of compounds of formula (I) is directed to compounds wherein V is —C(O)—; W is —N(R¹)C(O)—; R¹ is hydrogen; R² is C₄-C₁₂cycloalkylalkyl; R³ is C₇-C₁₂aralkyl optionally substituted with one or more substituents independently selected from halo or C₁-C₆trihaloalkyl; R⁴ and R⁵ are each hydrogen; and R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each hydrogen.

Another subgroup of this group of compounds of formula (I) is directed to compounds wherein V is —C(O)—; W is —N(R¹)C(O)—; R¹ is hydrogen; R² is C₄-C₁₂cycloalkylalkyl; R³ is C₃-C₁₂heterocyclyl or C₅-C₁₂ heteroaryl, each optionally substituted with one or more substituents independently selected from halo, C₁-C₆alkyl, C₁-C₆trihaloalkyl or aralkyl; R⁴ and R⁵ are each hydrogen; and R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each hydrogen.

In another embodiment of the invention as set forth above in the Summary of the Invention, a group of compounds of formula (I) is directed to compounds wherein x and y are each 1; V is —C(O)— or —C(S)—; W is selected from —C(O)N(R¹)— and —N(R¹)C(O)—; each R¹ is independently selected from hydrogen or C₁-C₆alkyl; R² is selected from the group consisting of C₁-C₁₂alkyl, C₂-C₁₂alkenyl, C₂-C₁₂hydroxyalkyl, C₂-C₁₂hydroxyalkenyl, C₁-C₆alkoxy, C₃-C₁₂alkoxyalkyl, C₃-C₁₂cycloalkyl, C₄-C₁₂cycloalkylalkyl, aryl, C₇-C₁₂aralkyl, C₃-C₁₂ heterocyclyl, C₃-C₁₂heterocyclylalkyl, C₁-C₁₂heteroaryl and C₃-C₁₂heteroarylalkyl; each R² is optionally substituted by one or more substituents selected from the group consisting of halo, cyano, oxo, thioxo, C₁-C₃alkyl, —OR¹¹, —C(O)R¹¹, —OC(O)R¹¹, —C(O)OR¹¹, —C(O)N(R¹²)₂, —N(R¹²)₂, C₁-C₆trihaloalkyl, cycloalkyl, heterocyclyl, aryl, heteroaryl and heteroarylcycloalkyl; R³ is phenyl optionally substituted by one or more substituents selected from the group consisting of halo, cyano, nitro, hydroxy, C₁-C₆alkyl, C₁-C₆trihaloalkyl, C₁-C₆trihaloalkoxy C₁-C₆alkylsulfonyl, —N(R¹²)₂, —OC(O)R¹¹, —C(O)OR¹¹, —S(O)₂N(R¹²)₂, cycloalkyl, heterocyclyl and heteroarylcycloalkyl; R⁴ and R⁵ are each independently selected from hydrogen, fluoro, chloro, methyl, methoxy and trifluoromethyl; R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each independently selected from hydrogen or C₁-C₃alkyl; R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each independently selected from hydrogen or C₁-C₃alkyl; or R⁶ and R^(6a) together or R⁹ and R^(9a) together are an oxo group, while the remaining R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each independently selected from hydrogen or C₁-C₃alkyl; each R¹¹ is independently selected from hydrogen, C₁-C₆alkyl, C₃-C₆cycloalkyl, aryl or aralkyl; and each R¹² is independently selected from hydrogen or C₁-C₆alkyl.

Of this group of compounds of formula (I), a subgroup of compounds is directed to compounds wherein x and y are each 1; V is C(O)— or —C(S)—; W is —N(R¹)C(O)—; R¹ is hydrogen, methyl or ethyl; R⁴ and R⁵ are each independently selected from hydrogen, fluoro, chloro, methyl, methoxy and trifluoromethyl; and R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each independently selected from hydrogen or C₁-C₃alkyl.

Of this subgroup of compounds of formula (I), a set of compounds is directed to compounds wherein R² is C₄-C₁₂cycloalkylalkyl optionally substituted by one or more substituents selected from the group consisting of —OR¹¹, C₁-C₃alkyl or aryl; R³ is phenyl optionally substituted by one or more substituents selected from the group consisting of halo, cyano, nitro, hydroxy, C₁-C₆alkyl, C₁-C₆trihaloalkyl, C₁-C₆trihaloalkoxy, C₁-C₆alkylsulfonyl, —N(R¹²)₂, —OC(O)R¹¹, —C(O)OR¹¹, —S(O)₂N(R¹²)₂ and cycloalkyl; each R¹¹ is independently selected from hydrogen, C₁-C₆alkyl, C₃-C₆cycloalkyl, aryl or aralkyl; and each R¹² is independently selected from hydrogen or C₁-C₆alkyl.

Another set of this subgroup of compounds of formula (I) is directed to compounds wherein V is —C(O)—; R² is C₁-C₁₂alkyl or C₂-C₁₂alkenyl, each optionally substituted by one or more substituents selected from the group consisting of halo, aryloxy, —C(O)R¹¹—OC(O)R¹¹ or —C(O)OR¹¹; R³ is phenyl optionally substituted by one or more substituents selected from the group consisting of halo, cyano, nitro, hydroxy, C₁-C₆alkyl, C₁-C₆trihaloalkyl, C₁-C₆trihaloalkoxy C₁-C₆alkylsulfonyl, —N(R¹²)₂, —OC(O)R¹¹, —C(O)OR¹¹, —S(O)₂N(R¹²)₂ and cycloalkyl; each R¹¹ is independently selected from hydrogen, C₁-C₆alkyl, C₃-C₆cycloalkyl, aralkyl or aryl (optionally substituted with one or more halo groups); and each R¹² is independently selected from hydrogen or C₁-C₆alkyl.

Another set of this subgroup of compounds of formula (I) is directed to compounds wherein V is —C(O)—; R² is C₂-C₁₂hydroxyalkyl, C₂-C₁₂hydroxyalkenyl, each optionally substituted by one or more halo groups; R³ is phenyl optionally substituted by one or more substituents selected from the group consisting of halo, cyano, nitro, hydroxy, C₁-C₆alkyl, C₁-C₆trihaloalkyl, C₁-C₆trihaloalkoxy C₁-C₆alkylsulfonyl, —N(R¹²)₂, —OC(O)R¹¹, —C(O)OR¹¹, —S(O)₂N(R¹²)₂ and cycloalkyl; each R¹¹ is independently selected from hydrogen, C₁-C₆alkyl, C₃-C₆cycloalkyl, aralkyl or aryl (optionally substituted with one or more halo groups); and each R¹² is independently selected from hydrogen or C₁-C₆alkyl.

Another set of this subgroup of compounds of formula (I) is directed to compounds wherein V is —C(O)—; R² is C₇-C₁₂aralkyl, where the aryl part of the C₇-C₁₂aralkyl group is optionally substituted by one or more substituents independently selected from halo, C₁-C₃alkyl, —OR¹¹, —C(O)OR¹¹, C₁-C₆trihaloalkyl, cycloalkyl and aryl, and the alkyl part of the C₇-C₁₂aralkyl group is optionally substituted by one or more substituents independently selected from hydroxy, halo, —OR¹¹ and —OC(O)R¹¹; R³ is phenyl optionally substituted by one or more substituents selected from the group consisting of halo, cyano, nitro, hydroxy, C₁-C₆alkyl, C₁-C₆trihaloalkyl, C₁-C₆trihaloalkoxy C₁-C₆alkylsulfonyl, —N(R¹²)₂, —OC(O)R¹¹, —C(O)OR¹¹, —S(O)₂N(R¹²)₂ and cycloalkyl; each R¹¹ is independently selected from hydrogen, C₁-C₆alkyl, C₃-C₆cycloalkyl, aralkyl or aryl (optionally substituted with one or more halo groups); and each R¹² is independently selected from hydrogen or C₁-C₆alkyl.

Another set of this subgroup of compounds of formula (I) is directed to compounds wherein V is —C(O)—; R² is C₁-C₆alkoxy or C₃-C₁₂alkoxyalkyl, each optionally substituted with one or more substituents independently selected from halo or C₃-C₆cycloalkyl; R³ is phenyl optionally substituted by one or more substituents selected from the group consisting of halo, cyano, nitro, hydroxy, C₁-C₆alkyl, C₁-C₆trihaloalkyl, C₁-C₆trihaloalkoxy C₁-C₆alkylsulfonyl, —N(R¹²)₂, —OC(O)R¹¹, —C(O)OR¹¹, —S(O)₂N(R¹²)₂ and cycloalkyl; each R¹¹ is independently selected from hydrogen, C₁-C₆alkyl, C₃-C₆cycloalkyl, aralkyl or aryl (optionally substituted with one or more halo groups); and each R¹² is independently selected from hydrogen or C₁-C₆alkyl.

Another set of this subgroup of compounds of formula (I) is directed to compounds wherein V is —C(O)—; R² is aryl optionally substituted with one or more substituents independently selected from halo, cyano, C₁-C₃alkyl, —OR¹¹, —C(O)R¹¹, —OC(O)R¹¹, —C(O)OR¹¹, —C(O)N(R¹²)₂, C₁-C₆trihaloalkyl, cycloalkyl, heterocyclyl, aryl, heteroaryl and heteroarylcycloalkyl; R³ is phenyl optionally substituted by C₁-C₆trihaloalkyl or C₁-C₆trihaloalkoxy; each R¹¹ is independently selected from hydrogen, C₁-C₆alkyl, C₃-C₆cycloalkyl, aralkyl or aryl (optionally substituted with one or more halo groups); and each R¹² is independently selected from hydrogen or C₁-C₆alkyl.

Another set of this subgroup of compounds of formula (I) is directed to compounds wherein V is —C(O)—; R² is C₁-C₁₂heteroaryl optionally substituted by one or more substituents selected from the group consisting of halo, cyano, oxo, thioxo, C₁-C₃alkyl, —OR¹¹, —C(O)R¹¹, —OC(O)R¹¹, —C(O)OR¹¹, —C(O)N(R¹²)₂ and C₁-C₆trihaloalkyl; R³ is phenyl optionally substituted by C₁-C₆trihaloalkyl or C₁-C₆trihaloalkoxy; each R¹¹ is independently selected from hydrogen, C₁-C₆alkyl, C₃-C₆cycloalkyl, aralkyl or aryl (optionally substituted with one or more halo groups); and each R¹² is independently selected from hydrogen or C₁-C₆alkyl.

Of this set of compounds of formula (I), a subset of compounds is directed to compounds wherein C₁-C₁₂heteroaryl is selected from the group consisting of pyridinyl, purinyl, pyrazinyl, indolyl, indazolyl, benzoimidazolyl, imidazolyl, tetrazolyl, triazolyl, isoxazolyl, pyrazolyl, pyrimidinyl, thiadiazolyl, thiazolyl and pyridazinyl.

Another set of this subgroup of compounds of formula (I) is directed to compounds wherein V is C(O)—; R² is C₃-C₁₂ heterocyclyl, C₃-C₁₂heterocyclylalkyl or C₃-C₁₂heteroarylalkyl, each optionally substituted by one or more substituents selected from the group consisting of halo, cyano, oxo, thioxo, C₁-C₃alkyl, —OR¹¹, —C(O)R¹¹, —OC(O)R¹¹, —C(O)OR¹¹, —C(O)N(R¹²)₂ and C₁-C₆trihaloalkyl; R³ is phenyl optionally substituted by halo, C₁-C₆trihaloalkyl or C₁-C₆trihaloalkoxy; each R¹¹ is independently selected from hydrogen, C₁-C₆alkyl, C₃-C₆cycloalkyl, aralkyl or aryl (optionally substituted with one or more halo groups); and each R¹² is independently selected from hydrogen or C₁-C₆alkyl.

Of the group of compounds of formula (I) as set forth above, another subgroup of compounds of formula (I) is directed to compounds wherein x and y are each 1; V is —C(O)—; W is —C(O)N(R¹)—; R¹ is hydrogen, methyl or ethyl; R⁴ and R⁵ are each independently selected from hydrogen, fluoro, chloro, methyl, methoxy and trifluoromethyl; and R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each independently selected from hydrogen or C₁-C₃alkyl.

Of this subgroup of compounds, a set of compounds of formula (I) is directed to compounds wherein R² is C₃-C₁₂cycloalkyl or C₄-C₁₂cycloalkylalkyl, each optionally substituted by one or more substituents selected from the group consisting of —OR¹¹, C₁-C₃alkyl, C₁-C₆trihaloalkyl or aryl; R³ is phenyl optionally substituted by one or more substituents selected from the group consisting of halo, C₁-C₆trihaloalkyl and C₁-C₆trihaloalkoxy; and each R¹¹ is independently selected from hydrogen, C₁-C₆alkyl, C₃-C₆cycloalkyl, aryl or aralkyl.

Another set of this subgroup of compounds of formula (I) is directed to compounds wherein R² is C₁-C₁₂alkyl, C₂-C₁₂alkenyl, C₁-C₆alkoxy or C₃-C₁₂alkoxyalkyl, each of which is optionally substituted by one or more substituents selected from the group consisting of halo, cyano, oxo, thioxo, C₁-C₃alkyl, —OR¹¹, —C(O)R¹¹, —OC(O)R¹¹, —C(O)OR¹¹, —C(O)N(R¹²)₂, —N(R¹²)₂, C₁-C₆trihaloalkyl, cycloalkyl and aryl; R³ is phenyl optionally substituted by halo, C₁-C₆trihaloalkyl or C₁-C₆trihaloalkoxy; each R¹¹ is independently selected from hydrogen, C₁-C₆alkyl, C₃-C₆cycloalkyl, aralkyl or aryl (optionally substituted with one or more halo groups); and each R¹² is independently selected from hydrogen or C₁-C₆alkyl.

Another set of this subgroup of compounds of formula (J) is directed to compounds wherein R² is C₇-C₁₂aralkyl optionally substituted by one or more substituents selected from the group consisting of halo, cyano, oxo, thioxo, C₁-C₃alkyl, —OR¹¹, —C(O)R¹¹, —OC(O)R¹¹, —C(O)OR¹¹, —C(O)N(R¹²)₂, —N(R¹²)₂, C₁-C₆trihaloalkyl, cycloalkyl and aryl; R³³ is phenyl optionally substituted by halo, C₁-C₆trihaloalkyl or C₁-C₆trihaloalkoxy; each R¹¹ is independently selected from hydrogen, C₁-C₆alkyl, C₃-C₆cycloalkyl, aralkyl or aryl (optionally substituted with one or more halo groups); and each R¹² is independently selected from hydrogen or C₁-C₆alkyl.

In another embodiment of the invention as set for above in the Summary of the Invention, another group of compounds of formula (I) is directed to compounds wherein x and y are each 1; V is —C(O)—; W is —N(R¹)C(O)—; R¹ is hydrogen, methyl or ethyl; R² is cyclopropylethyl or cyclopropylmethyl; R³ is phenyl optionally substituted by one or more substituents selected from the group consisting of fluoro, chloro and trifluoromethyl; R⁴ and R⁵ are each hydrogen; and R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹ and R^(9a) are each hydrogen.

In another embodiment of the invention as set for above in the Summary of the Invention, another group of compounds of formula (I) is directed to compounds wherein x and y are each 1; V is —C(O)—; W is —N(R¹)C(O)—; R¹ is hydrogen, methyl or ethyl; R² is C₁-C₆alkyl optionally substituted by —C(O)OR¹¹; R³ is phenyl optionally substituted by one or more substituents selected from the group consisting of fluoro, chloro and trifluoromethyl; R⁴ and R⁵ are each hydrogen; R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each hydrogen; and R¹¹ is hydrogen, methyl, ethyl or 1,1-dimethylethyl.

In another embodiment of the invention as set for above in the Summary of the Invention, another group of compounds of formula (I) is directed to compounds wherein x and y are each 1; V is —C(O)—; W is —N(R¹)C(O)—; R¹ is hydrogen, methyl or ethyl; R² is 2-phenylethyl or 3-phenylpropyl where the phenyl group is optionally substituted by one or more substituents independently selected from chloro, fluoro or —OR¹¹; R³ is phenyl optionally substituted by one or more substituents selected from the group consisting of fluoro, chloro and trifluoromethyl; R⁴ and R⁵ are each hydrogen; R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each hydrogen; and R¹¹ is hydrogen, methyl, ethyl or 1,1-dimethylethyl.

In another embodiment of the invention as set for above in the Summary of the Invention, another group of compounds of formula (I) is directed to compounds wherein x and y are each 1; V is —C(O)—; W is —C(O)N(R¹)—; R¹¹ is hydrogen, methyl or ethyl; R¹¹ is cyclopropylethyl, cyclopropylmethyl or cyclopentylethyl; R³ is phenyl optionally substituted by one or more substituents selected from the group consisting of fluoro, chloro and trifluoromethyl; R⁴ and R⁵ are each independently selected from hydrogen, fluoro, chloro, methyl, methoxy and trifluoromethyl; and R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹ and R^(9a) are each hydrogen.

In another embodiment of the invention as set for above in the Summary of the Invention, another group of compounds of formula (I) is directed to compounds wherein x and y are each 1; V is —C(O)—; W is —C(O)N(R¹)—; R¹ is hydrogen, methyl or ethyl; R² is C₁-C₆alkyl; R³ is phenyl optionally substituted by one or more substituents selected from the group consisting of fluoro, chloro and trifluoromethyl; R⁴ and R⁵ are each independently selected from hydrogen, fluoro, chloro, methyl, methoxy and trifluoromethyl; and R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each hydrogen.

In another embodiment of the invention as set for above in the Summary of the Invention, another group of compounds of formula (I) is directed to compounds wherein x and y are each 1; V is —C(O)—; W is —C(O)N(R¹)—; R¹ is hydrogen, methyl or ethyl; R² is 3-phenylpropyl; R³ is phenyl optionally substituted by one or more substituents selected from the group consisting of fluoro, chloro and trifluoromethyl; R⁴ and R⁵ are each independently selected from hydrogen, fluoro, chloro, methyl, methoxy and trifluoromethyl; and R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each hydrogen.

In another embodiment of the invention as set forth above in the Summary of the Invention, a group of compounds of formula (I) is directed to compounds wherein x and y are each 1; V is —C(O)—; W is —N(R¹)C(O)N(R¹)—; each R¹ is hydrogen or C₁-C₆alkyl; R² is selected from the group consisting of C₃-C₁₂alkyl, C₃-C₁₂alkenyl, C₃-C₁₂hydroxyalkyl, C₃-C₁₂hydroxyalkenyl, C₃-C₁₂alkoxyalkyl, C₃-C₁₂cycloalkyl, C₄-C₁₂cycloalkylalkyl, C₃-C₁₂heterocyclyl, C₃-C₁₂heterocyclylalkyl, aryl, C₇-C₁₂aralkyl, C₁-C₁₂heteroaryl, and C₃-C₁₂heteroarylalkyl; each R¹² is optionally substituted by one or more substituents selected from the group consisting of halo, oxo, thioxo, C₁-C₃alkyl, —OR¹¹, —C(O)OR¹¹, C₁-C₆trihaloalkyl, cycloalkyl, heterocyclyl, aryl, heteroaryl and heteroarylcycloalkyl; R³ is selected from the group consisting of C₃-C₁₂alkyl, C₃-C₁₂alkenyl, C₃-C₁₂hydroxyalkyl, C₃-C₁₂ hydroxyalkenyl, C₃-C₁₂alkoxy, C₃-C₁₂alkoxyalkyl, C₃-C₁₂cycloalkyl, C₄-C₁₂cycloalkylalkyl, aryl, C₇-C₁₂aralkyl, C₃-C₁₂heterocyclyl, C₃-C₁₂heterocyclylalkyl, C₁-C₁₂heteroaryl and C₃-C₁₂heteroarylalkyl; where each of the above R³ groups are optionally substituted by one or more substituents selected from the group consisting of C₁-C₆alkyl, C₁-C₆trihaloalkyl, C₁-C₆trihaloalkoxy, C₁-C₆alkoxy, C₁-C₆alkylsulfonyl, halo, cyano, nitro, hydroxy, —N(R¹²)₂, —C(O)OR¹¹, —S(O)₂N(R¹²)₂, cycloalkyl, heterocyclyl, aryl, heteroaryl and heteroarylcycloalkyl; R⁴ and R⁵ are each independently selected from hydrogen, fluoro, chloro, methyl, methoxy and trifluoromethyl; R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each independently selected from hydrogen or C₁-C₃alkyl; R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each independently selected from hydrogen or C₁-C₃alkyl; or R⁶ and R^(6a) together or R⁷ and R^(7a) together are an oxo group while the remaining R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each independently selected from hydrogen or C₁-C₃alkyl; or one of R⁶, R^(6a), R⁷, and R^(7a) together with one of R⁸, R^(8a), R⁹ and R^(9a) form an alkylene bridge, while the remaining R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each independently selected from hydrogen or C₁-C₃alkyl; each R¹¹ is independently selected from hydrogen, C₁-C₆alkyl, C₃-C₆alkyl, aryl or aralkyl; and each R¹² is independently selected from hydrogen or C₁-C₆alkyl.

Of this group of compounds of formula (I), a subgroup of compounds is directed to compounds wherein R² is C₃-C₁₂cycloalkyl or C₄-C₁₂cycloalkylalkyl, each optionally substituted by one or more substituents selected from the group consisting of —OR¹¹, C₁-C₃alkyl or aryl; R³ is phenyl optionally substituted by one or more substituents selected from the group consisting of halo, C₁-C₆trihaloalkyl and C₁-C₆trihaloalkoxy; and each R¹¹ is independently selected from hydrogen, C₁-C₆alkyl, C₃-C₆cycloalkyl, aryl or aralkyl.

Another subgroup of this group of compounds of formula (I) is directed to compounds wherein R² is C₇-C₁₂aralkyl optionally substituted by one or more substituents selected from the group consisting of halo, —OR¹¹ or C₁-C₃alkyl; R³ is phenyl optionally substituted by one or more substituents selected from the group consisting of halo, C₁-C₆trihaloalkyl and C₁-C₆trihaloalkoxy; and each R¹¹ is independently selected from hydrogen, C₁-C₆alkyl, C₃-C₆cycloalkyl, aryl or aralkyl.

Another subgroup of this group of compounds of formula (J) is directed to compounds wherein R² is aryl optionally substituted by one or more substituents selected from the group consisting of halo, —OR¹¹ or C₁-C₃alkyl; R³ is phenyl optionally substituted by one or more substituents selected from the group consisting of halo, C₁-C₆trihaloalkyl and C₁-C₆trihaloalkoxy; and each R¹¹ is independently selected from hydrogen, C₁-C₆alkyl, C₃-C₆cycloalkyl, aryl or aralkyl.

Another subgroup of this group of compounds of formula (I) is directed to compounds wherein R² is C₃-C₁₂alkyl, C₃-C₁₂hydroxyalkyl or C₃-C₁₂alkoxyalkyl, each optionally substituted by one or more substituents selected from the group consisting of halo, —OR¹¹ or —C(O)OR¹¹; R³ is phenyl optionally substituted by one or more substituents selected from the group consisting of halo, C₁-C₆trihaloalkyl and C₁-C₆trihaloalkoxy; and each R¹¹ is independently selected from hydrogen, C₁-C₆alkyl, C₃-C₆cycloalkyl, aryl or aralkyl.

In another embodiment of the invention as set for above in the Summary of the Invention, another group of compounds of formula (I) is directed to compounds wherein x and y are each 1; V is —C(O)—; W is —N(R¹)C(O)N(R¹)—; each R¹ is hydrogen, methyl or ethyl; R² is benzyl; R³ is phenyl optionally substituted by one or more substituents selected from the group consisting of fluoro, chloro and trifluoromethyl; R⁴ and R⁵ are each independently selected from hydrogen, fluoro, chloro, methyl, methoxy and trifluoromethyl; and R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each hydrogen.

In another embodiment of the invention as set for above in the Summary of the Invention, another group of compounds of formula (I) is directed to compounds wherein x and y are each 1; V is —C(O)—; W is —N(R¹)C(O)N(R¹)—; each R¹ is hydrogen, methyl or ethyl; R² is pentyl; R³ is phenyl optionally substituted by one or more substituents selected from the group consisting of fluoro, chloro and trifluoromethyl; R⁴ and R⁵ are each independently selected from hydrogen, fluoro, chloro, methyl, methoxy and trifluoromethyl; and R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each hydrogen.

In another embodiment of the invention as set forth above in the Summary of the Invention, a group of compounds of formula (I) is directed to compounds wherein x and y are each independently 1; V is —C(R¹⁰)H; W is —N(R¹)C(O)—; each R¹ is hydrogen or C₁-C₆alkyl; R² is selected from the group consisting of C₇-C₁₂alkyl, C₂-C₁₂alkenyl, C₇-C₁₂hydroxyalkyl, C₂-C₁₂hydroxyalkenyl, C₁-C₁₂alkoxy, C₂-C₁₂alkoxyalkyl, C₃-C₁₂cycloalkyl, C₄-C₁₂cycloalkylalkyl, C₁₃-C₁₉aralkyl, C₃-C₁₂heterocyclyl, C₃-C₂heterocyclylalkyl, C₁-C₁₂heteroaryl, and C₃-C₁₂heteroarylalkyl; each R² is optionally substituted by one or more substituents selected from the group consisting of halo, cyano, oxo, thioxo, C₁-C₃alkyl, —OR¹¹, —C(O)R¹¹, —OC(O)R¹¹, —C(O)OR¹¹, —C(O)N(R¹²)₂, —N(R¹²)₂, C₁-C₆trihaloalkyl, cycloalkyl, heterocyclyl, aryl, heteroaryl and heteroarylcycloalkyl; R³ is selected from the group consisting of C₁-C₁₂alkyl, C₂-C₁₂alkenyl, C₂-C₁₂hydroxyalkyl, C₂-C₁₂hydroxyalkenyl, C₁-C₁₂alkoxy, C₂-C₁₂alkoxyalkyl, C₃-C₁₂cycloalkyl, C₄-C₁₂cycloalkylalkyl, aryl, C₇-C₁₂aralkyl, C₃-C₁₂heterocyclyl, C₃-C₁₂heterocyclylalkyl, C₁-C₁₂heteroaryl and C₃-C₁₂heteroarylalkyl; each R³ is optionally substituted by one or more substitutents selected from the group consisting of halo, cyano, nitro, hydroxy, C₁-C₆alkyl, C₁-C₆trihaloalkyl, C₁-C₆trihaloalkoxy C₁-C₆alkylsulfonyl, —N(R¹²)₂, —OC(O)R¹¹, —C(O)OR¹¹, —S(O)₂N(R¹²)₂, cycloalkyl, heterocyclyl and heteroarylcycloalkyl; R⁴ and R⁵ are each independently selected from hydrogen, fluoro, chloro, methyl, methoxy, trifluoromethyl, cyano, nitro or —N(R¹²)₂; R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each independently selected from hydrogen or C₁-C₃alkyl; R¹⁰ is hydrogen or C₁-C₃alkyl; each R¹¹ is independently selected from hydrogen, C₁-C₆alkyl, C₃-C₆Cycloalkyl, aryl or aralkyl; and each R¹² is independently selected from hydrogen or C₁-C₆alkyl.

Of this group of compounds of formula (I), a subgroup of compounds is directed to compounds wherein R² is C₃-C₁₂cycloalkyl or C₄-C₁₂cycloalkylalkyl, each optionally substituted by one or more substituents selected from the group consisting of halo, C₁-C₆trihaloalkyl, —OR¹¹, C₁-C₃alkyl or aryl; R³ is phenyl optionally substituted by one or more substituents selected from the group consisting of halo, cyano, nitro, hydroxy, C₁-C₆alkyl, C₁-C₆trihaloalkyl, C₁-C₆trihaloalkoxy, C₁-C₆alkylsulfonyl, —N(R¹²)₂, —OC(O)R¹¹, —C(O)OR¹¹, —S(O)₂N(R¹²)₂ and cycloalkyl; each R¹¹ is independently selected from hydrogen, C₁-C₆alkyl, C₃-C₆cycloalkyl, aryl or aralkyl; and each R¹² is independently selected from hydrogen or C₁-C₆alkyl.

Specific embodiments of the above-described groups, subgroups and sets of compounds of formula (I) are disclosed herein in the Examples set forth below.

In one embodiment, the methods of the invention are directed towards the treatment and/or prevention of diseases mediated by stearoyl-CoA desaturase (SCD), especially human SCD (hSCD), preferably the diseases are skin disorders, such as acne, rosacea, seborrheic skin, and the like by administering an effective amount of a compound of the invention.

The present invention also relates to pharmaceutical composition containing the compounds of the invention. In one embodiment, the invention relates to a composition comprising compounds of the invention in a pharmaceutically acceptable carrier and in an amount effective to modulate the SCD activity or to treat skin disorders mediated by SCD, such as acne, rosacea, and seborrheic skin, when administered to an animal, preferably a mammal, most preferably a human patient. In an embodiment of such composition, the patient may have elevated levels of sebum production or the number or the size of sebaceous glands in skin, before administration of said compound of the invention and the compound of the invention is present in an amount effective to reduce said sebum production or sebaceous gland numbers/sizes.

Utility and Testing of the Compounds of the Invention

The present invention relates to compounds, pharmaceutical compositions and methods of using the compounds and pharmaceutical compositions for the treatment and/or prevention of diseases mediated by stearoyl-CoA desaturase (SCD), especially human SCD (hSCD), preferably skin disorders such as acne, rosacea, and seborrheic skin, by administering to a patient in need of such treatment an effective amount of an SCD-modulating, especially inhibiting, agent.

As used herein, the term “rosacea” is a recognized clinical term used to describe a condition comprising erythema (flushing and redness) on the central face and across the cheeks, nose, neck, chest, or forehead, telangiectasia (dilation of superficial blood vessels on the face), red domed papules (small bumps) and pustules, red gritty eyes, burning and stinging sensations, and red lobulated nose (rhinophyma).

As used herein, the term “seborrheic skin” (or “seborrheic dermatitis”) is a recognized clinical term used to describe a condition comprising scaly, flaky, itchy, red skin on the scalp, face, and trunk.

Embodiments of the invention provide methods for treating or protecting a skin disorder such as acne, rosacea, and seborrheic skin, comprising administering to an animal, such as a mammal, especially a human patient, a therapeutically effective amount of a compound of the invention or a pharmaceutical composition comprising a compound of the invention wherein the compound modulates (preferably inhibits) the activity of SCD, preferably human SCD1.

In accordance with embodiments of the invention, modulation or inhibition of the activity of SCD can be determined using any assay known in the art, such as that described below in Example 33. Similarly, the general value of compounds of the invention in treating skin disorders or diseases may be assessed using industry standard animal models to demonstrate the efficacy of these compounds in treating skin disorders, such as acne, rosacea, or seborrheic skin.

Compounds of the invention are inhibitors of delta-9 desaturases (e.g., SCD) and are useful for treating or preventing diseases and disorders that arise from aberrant delta-9 desaturase (e.g., SCD) activity.

An SCD-mediated disease or condition also includes a disorder of polyunsaturated fatty-acid (PUFA) disorder, or a skin disorder, including but not limited to eczema, acne, rosacea, seborrheic skin, psoriasis, keloid scar formation or prevention, diseases related to production or secretions from mucous membranes, such as monounsaturated fatty acids, wax esters, and the like. In a preferred embodiment, compounds of the invention may be used to treat a skin disorder or condition such as acne, rosacea, and seborrheic skin.

The compounds identified in the instant specification inhibit the desaturation of various fatty acids (such as the C9-C10 desaturation of stearoyl-CoA) by delta-9 desaturases, such as stearoyl-CoA desaturase 1 (SCD1). As such, these compounds inhibit the formation of various fatty acids and downstream metabolites thereof. This may lead to an accumulation of stearoyl-CoA or palmitoyl-CoA and other upstream precursors of various fatty acids, which may possibly result in a negative feedback loop causing an overall change in fatty acid metabolism. Any of these consequences may ultimately be responsible for the overall therapeutic benefit provided by these compounds.

Typically, a successful SCD inhibitory therapeutic agent will meet some or all of the following criteria. Oral availability should be at or above 20%. Animal model efficacy is less than about 2 mg/Kg, 1 mg/Kg, or 0.5 mg/Kg and the target human dose is between 50 and 250 mg/70 Kg, although doses outside of this range may be acceptable. (“mg/Kg” means milligrams of compound per kilogram of body mass of the subject to whom it is being administered). The therapeutic index (or ratio of toxic dose to therapeutic dose) should be greater than 100. The potency (as expressed by IC₅₀ value) should be less than 10 μM, preferably below 1 μM and most preferably below 50 nM. The IC₅₀ is the concentration of a compound required to achieve 50% inhibition of SCD activity. Any process for measuring the activity of SOD enzymes, preferably mouse or human SCD enzymes, may be utilized to assay the activity of the compounds. Compounds of the invention demonstrate an IC₅₀ in a microsomal assay of preferably less than 10 μM, less than 5 μM, less than 2.5 μM, less than 1 μM, less than 750 nM, less than 500 nM, less than 250 nM, less than 100 nM, less than 50 nM, and most preferably less than 20 nM. The compound of the invention may show reversible inhibition (i.e., competitive inhibition) and preferably does not inhibit other iron binding proteins.

The identification of compounds of the invention as SCD inhibitors was readily accomplished using the SCD enzyme and microsomal assay procedure described in Brownlie et al, supra. When tested in this assay, compounds of the invention had less than 50% remaining SCD activity at 10 μM concentration of the test compound, preferably less than 40% remaining SCD activity at 10 μM concentration of the test compound, more preferably less than 30% remaining SOD activity at 10 μM concentration of the test compound, and even more preferably less than 20% remaining SCD activity at 10 μM concentration of the test compound, thereby demonstrating that the compounds of the invention are potent inhibitors of SCD activity.

These results provide the basis for analysis of the structure-activity relationship (SAR) between test compounds and SCD. Certain R groups tend to provide more potent inhibitory compounds. SAR analysis is one of the tools those skilled in the art may now employ to identify preferred embodiments of the compounds of the invention for use as therapeutic agents.

Other methods of testing the compounds disclosed herein are also readily available to those skilled in the art. Thus, in addition, said contacting may be accomplished in vivo. In one such embodiment, a compound of the invention may be administered (preferably by topical application) to a subject afflicted with a skin disorder and wanting to prevent a skin disorder.

In specific embodiments of such in vivo processes, said change in SCD1 activity in said animal is a decrease in activity, preferably wherein said SCD1 modulating agent does not substantially inhibit the biological activity of a delta-5 desaturase, delta-6 desaturase or fatty acid synthetase.

The model systems useful for compound evaluation may include, but are not limited to, the use of liver microsomes, such as from mice. Another suitable method for determining the in vivo efficacy of the compounds of the invention is to indirectly measure their impact on inhibition of SCD enzyme by measuring a subject's Desaturation Index after administration of the compound. “Desaturation Index” as employed in this specification means the ratio of the product over the substrate for the SCD enzyme as measured from a given tissue sample. This may be calculated using three different equations 18.1n−9/18:0 (oleic acid over stearic acid); 16:1n−7/16:0 (palmitoleic acid over palmitic acid); and/or 16:1n−7+18.1n−7/16:0 (measuring all reaction products of 16:0 desaturation over 16:0 substrate). Desaturation Index is primarily measured in liver or plasma triglycerides, but may also be measured in other selected lipid fractions from a variety of tissues. Desaturation Index, generally speaking, is a tool for plasma lipid profiling.

In carrying out the procedures of the present invention, it is of course to be understood that reference to particular buffers, media, reagents, cells, culture conditions and the like are not intended to be limiting, but are to be read so as to include all related materials that one of ordinary skill in the art would recognize as being of interest or value in the particular context in which that discussion is presented. For example, it is often possible to substitute one buffer system or culture medium for another and still achieve similar, if not identical, results. Those of skill in the art will have sufficient knowledge of such systems and methodologies so as to be able, without undue experimentation, to make such substitutions as will optimally serve their purposes in using the methods and procedures disclosed herein.

Pharmaceutical Compositions of the Invention and Administration

The present invention also relates to pharmaceutical compositions containing compounds of the invention. In one embodiment, the present invention relates to compositions comprising compounds of the invention in a pharmaceutically acceptable carrier. The compounds or compositions of the invention may be prepared in any suitable dosage forms, including oral dosage, injections, and topical dosages (e.g., solutions, lotions, creams, paste, emulsions, suspensions, etc.). If prepared for topical applications, the compositions may further comprise an enhancer for skin penetration, such as SEPA 09. In such preparations, the compounds of the invention will be in an amount or concentration sufficient to effect modulation or inhibition of SCD.

The pharmaceutical compositions useful herein may contain a pharmaceutically acceptable carrier, including any suitable diluent or excipient, which includes any pharmaceutical agent that does not itself induce the production of antibodies harmful to the individual receiving the composition, and which may be administered without undue toxicity. Pharmaceutically acceptable carriers include, but are not limited to, liquids, such as water, saline, glycerol and ethanol, and the like. A thorough discussion of pharmaceutically acceptable carriers, diluents, and other excipients is presented in REMINGTON'S PHARMACEUTICAL SCIENCES (Mack Pub. Co., N.J. current edition).

Those skilled in the art know how to determine suitable doses of the compounds for use in treating the diseases and disorders contemplated herein. Therapeutic doses are generally identified through a dose ranging study in humans based on preliminary evidence derived from animal studies.

Doses must be sufficient to result in a desired therapeutic benefit without causing unwanted side-effects for the patient. The preferred dosage range for an animal is 0.001 mg/Kg to 10,000 mg/Kg, including 0.5 mg/Kg, 1.0 mg/Kg and 2.0 mg/Kg, though doses outside this range may be acceptable. The dosing schedule may be once or twice per day, although more often or less often may be satisfactory.

Those skilled in the art are also familiar with determining administration methods (oral, intravenous, inhalation, sub-cutaneous, topical, etc.), dosage forms, suitable pharmaceutical excipients and other matters relevant to the delivery of the compounds to a subject in need thereof.

In an alternative use of the invention, the compounds of the invention can be used in in vitro or in vivo studies as exemplary agents for comparative purposes to find other compounds also useful in treatment of or protection from, the various diseases disclosed herein.

Preparation of the Compounds of the Invention

It is understood that in the following description, combinations of substituents and/or variables of the depicted formulae are permissible only if such contributions result in stable compounds.

It will also be appreciated by those skilled in the art that in the process described below, the functional groups of intermediate compounds may need to be protected by suitable protecting groups. Such functional groups include hydroxy, amino, mercapto and carboxylic acid. Suitable protecting groups for hydroxy include trialkylsilyl or diarylalkylsilyl (e.g., t-butyldimethylsilyl, t-butyldiphenylsilyl or trimethylsilyl), tetrahydropyranyl, benzyl, and the like. Suitable protecting groups for amino, amidino and guanidino include t-butoxycarbonyl, benzyloxycarbonyl, and the like. Suitable protecting groups for mercapto include —C(O)—R″ (where R″ is alkyl, aryl or arylalkyl), p-methoxybenzyl, trityl and the like. Suitable protecting groups for carboxylic acid include alkyl, aryl or arylalkyl esters.

Protecting groups may be added or removed in accordance with standard techniques, which are well-known to those skilled in the art and as described herein.

The use of protecting groups is described in detail in Green, T. W. and P. G. M. Wutz, Protective Groups in Organic Synthesis (1999), 3rd Ed., Wiley. The protecting group may also be a polymer resin such as a Wang resin or a 2-chlorotrityl-chloride resin.

It will also be appreciated by those skilled in the art, although such protected derivatives of compounds of this invention may not possess pharmacological activity as such, they may be administered to a mammal and thereafter metabolized in the body to form compounds of the invention which are pharmacologically active. Such derivatives may therefore be described as “prodrugs”. All prodrugs of compounds of this invention are included within the scope of the invention.

The following Reaction Schemes illustrate methods to make compounds of this invention. It is understood that one of those skilled in the art would be able to make these compounds by similar methods or by methods known to one skilled in the art. In general, starting components may be obtained from sources such as Sigma Aldrich, Lancaster Synthesis, Inc., Maybridge, Matrix Scientific, TCI, and Fluorochem USA, etc. or synthesized according to sources known to those skilled in the art (see, e.g., Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, 5th edition (Wiley, December 2000)) or prepared as described in this invention.

In general, the compounds of formula (I) of this invention where W is —N(R¹)C(O)— can be synthesized following the general procedure as described in Reaction Scheme 1.

The starting materials for the above reaction scheme are commercially available or can be prepared according to methods known to one skilled in the art or by methods disclosed herein. In general, the compounds of the invention are prepared in the above reaction scheme as follows:

Compound 101. A carboxylic acid of formula (100) can easily be converted to an ester of formula (101) following a standard procedure known to one skilled in the art.

Compound 102. A mixture of a compound of formula (101) obtained above and phosphorous oxychloride is carefully heated to reflux for 2-8 hours. The reaction mixture is then cooled and excess phosphorous oxychloride is removed. The residue is then poured into ice water. The precipitate obtained is collected by filtration, washed with saturated NaHCO₃ and water, and then dried to yield the compound of formula (102).

Compound 104. A mixture of the compound of formula (102) (1 equivalent) and the compound of formula (103) (3 equivalent) in a solvent, such as N,N-dimethylformamide or acetonitrile, is refluxed for 1-4 hours. The solvent is then removed in vacuo. The residue is dissolved in a solvent such as dichloromethane or ethyl acetate. The resulting solution is washed with water, brine, and then dried. The organic phase was concentrated in vacuo to afford the compound of formula (104).

Compound 106. To a stirred solution of the compound of formula (104) (1 equivalent) in a solvent such as dichloromethane, toluene or THF is added the solution of a chloride or bromide of formula (105) (1 equivalent) in the presence of a base such as triethylamine or Hünigs base at 0° C. The resulting mixture is stirred at ambient temperature for 6-18 hours and then quenched with water. The organic phase is washed with water, brine, dried and then concentrated in vacuo to afford the product of formula (106) which is further purified by chromatography or crystallization.

Compound 107. A solution of a compound of formula (106) obtained above is dissolved in an adequate solvent and the ester is converted to a carboxylic acid under a standard condition known to one skilled in the art to obtain the carboxylic acid of formula (107).

Compound of formula (I). To a solution of a compound of formula (107) (1 equivalent) in a solvent, such as dichloromethane, toluene or THF, is added a base, such as triethylamine or Hunigs base (2.5 equivalent), followed by the addition of a coupling agent such as N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide (1.1 equivalent). The resulting mixture is stirred for 15 minutes to an hour and an amine of formula (108) (1.1 equivalent) is added. The mixture is stirred for 8-24 hours, then washed with water, dried and concentrated in vacuo. Purification by column chromatography or crystallization from a suitable solvent affords the compound of formula (I).

Alternatively, compounds of formula (I) of this invention where W is —N(R¹)C(O)— can be synthesized following the general procedure as described in Reaction Scheme 2.

The starting materials for the above reaction scheme are commercially available or can be prepared according to methods known to one skilled in the art or by methods disclosed herein. In general, the compounds of the invention are prepared in the above reaction scheme as follows:

Compound 111. To a solution of substituted 6-chloropyridazinyl-3-carboxylic acid of formula (109) (1 equivalent) in a solvent, such as dichloromethane, toluene or THF, is added a base, such as triethylamine or Hunigs base (2.5 equivalent), followed by the addition of a coupling agent such as N-(3-dimethylaminopropyl)-N-7-ethylcarbodiimide (1.1 equivalent). The resulting mixture is stirred for 15 minutes to an hour and an amine of formula (110) (1.1 equivalent) is added. The mixture is stirred for 8-24 hours, then washed with water, dried and concentrated in vacuo. Purification by column chromatography or crystallization from a suitable solvent affords the compound of formula (111).

Compound 113. A mixture of the compound of formula (111) (1 equivalent) and the compound of formula (112) (3 equivalent) in a solvent, such as N,N-dimethylformamide or acetonitrile, is refluxed for 1-4 hours. The solvent is then removed in vacuo. The residue is dissolved in a solvent such as dichloromethane or ethyl acetate. The resulting solution is washed with water, brine, and then dried. The organic phase was concentrated in vacuo to afford the compound of formula (113).

Compound of Formula (I). To a stirred solution of the compound of formula (113) (1 equivalent) in a solvent, such as dichloromethane, toluene or THF, is added the solution of a chloride or bromide of formula (114) (1 equivalent) in the presence of a base, such as triethylamine or Hunigs base, at 0° C. The resulting mixture is stirred at ambient temperature for 6-18 hours and then quenched with water. The organic phase is washed with water, brine, dried and then concentrated in vacuo to afford the compound of formula (I) which is further purified by chromatography or crystallization.

Alternatively, compounds of formula (I) of this invention where W is —C(O)N(R¹)— can be synthesized following the general procedure as described in Reaction Scheme 3.

The starting materials for the above reaction scheme are commercially available or can be prepared according to methods known to one skilled in the art or by methods disclosed herein. In general, the compounds of the invention are prepared in the above reaction scheme as follows:

Compound 117. To a stirred solution of the amine of formula (115) (1 equivalent) in a solvent, such as dichloromethane or toluene, is added the solution of a chloride or bromide of formula (116) (1 equivalent) in a solvent, such as dichloromethane or toluene, in the presence of a base such as triethylamine or Hunigs base. The resulting mixture is stirred at ambient temperature for an adequate time period and then quenched with water. The organic phase is washed with water, brine, dried and then concentrated in vacuo to afford the product of formula (117).

Compound 118. A solution of compound of formula (117) obtained above is dissolved in an adequate solvent and the protecting group R′ is removed under standard deprotection conditions such as hydrolysis or hydrogenation to obtain the amine of formula (118).

Compound 120. A mixture of a chloropyridazine of formula (119) (1 equivalent) and the amine of formula (118) obtained above (1.5 equivalent) in an adequate solvent is heated at reflux for 4-24 hours. To the reaction mixture is added a basic solution such as NaOH solution. The aqueous layer is extracted by an organic solvent such as dichloromethane or ethyl acetate. The combined organic phase is dried, then evaporated to dryness. The crude compound is purified by column chromatography or crystallization to afford the compound of formula (120).

Compound of Formula (I).

Method A. To a stirred solution of compound of formula (120) (1 equivalent) in a solvent, such as dichloromethane, acetonitrile or toluene, is added the solution of a compound of formula (121) (1 equivalent) in the presence of a base such as triethylamine or Hunigs base (1 equivalent) at 0° C. The resulting mixture is stirred at ambient temperature for 8-24 hours and then quenched with water. The organic phase is washed with water, brine, dried and then concentrated in vacuo. Further purification by column chromatography or crystallization from a suitable solvent affords the compound of formula (I).

Method B. To a solution of a carboxylic acid of formula (122) (1 equivalent) in a solvent, such as dichloromethane, toluene or THF, is added a base such as triethylamine or Hunigs base (2.5 equivalent), followed by the addition of a coupling agent such as (3-dimethylaminopropyl)ethyl carbodiimide (1.1 equivalent). The resulting mixture is stirred for 15 minutes to an hour and an amine of formula (120) (1.1 equivalent) is added. The mixture is stirred at ambient temperature for 8-24 hours, then washed with water, dried and concentrated in vacuo. Purification by column chromatography or crystallization from a suitable solvent affords the compound of formula (I).

Alternatively, compounds of formula (IV) of this invention can be synthesized following the general procedure as described in Reaction Scheme 4.

The starting materials for the above reaction scheme are commercially available or can be prepared according to methods known to one skilled in the art or by methods disclosed herein. In general, the compounds of the invention are prepared in the above reaction scheme as follows:

Compound of Formula (IV):

Method C. To a stirred solution of the compound of formula of (120) (1 equivalent) in an anhydrous solvent such as DMF is added an isocyanate of formula (123) (3 equivalent), and the mixture is then heated to 60-80° C. for 4-24 hours. The mixture is concentrated in vacuo. Purification of the crude product by column chromatography or crystallization from a suitable solvent affords the compound of Formula (IV).

Method D. A compound of formula (120) (1 equivalent) is slowly added to an ice cold solution of 1,1′-carbonyldiimidazole (1.5 to 2.5 equivalent) in an anhydrous solvent such as dichloromethane. The temperature is then raised to ambient temperature and the reaction mixture is stirred for another 2-8 hours. An amine of formula (124) (1 equivalent) is then added to the reaction mixture which is stirred at ambient temperature overnight under nitrogen atmosphere. The reaction mixture is then washed with saturated sodium bicarbonate and brine solution, concentrated and purified by flash column chromatography to afford the compound of formula (IV).

Although anyone skilled in the art is capable of preparing the compounds of the invention according to the general techniques disclosed above, more specific details on synthetic techniques for compounds of the invention are provided elsewhere in this specification for convenience. Again, all reagents and reaction conditions employed in synthesis are known to those skilled in the art and are available from ordinary commercial sources.

Preparation 1 Synthesis of 2-cyclopropylethylamine

Concentrated sulfuric acid (20.66 mL) was added dropwise to a vigorously stirred suspension of lithium aluminum hydride (764.4 mmol) in 800 mL of anhydrous ethyl ether (40 mL) at 0° C. for at least 2 hour period. The reaction mixture was warmed to ambient temperature and stirred for 1 hour, and a solution of cyclopropylacetonitrile (246.5 mmol) in 100 mL of anhydrous ethyl ether was added dropwise. The resulting mixture was heated to reflux for 2 hours, then cooled to 0° C., cautiously quenched with crushed ice. A solution of 38 g of NaOH in 350 mL of water was added, and the organic layer was decanted from the resulting aluminum hydroxide precipitate. The precipitate was washed thoroughly with ethyl ether (3×600 mL). All ethereal extracts were combined, dried over anhydrous Na₂SO₄ and the solvent was distilled off to afford 172.5 mmol of 2-cyclopropylethylamine as a colorless liquid (bp ˜100-108° C.). Yield 70%.

Preparation 2 Synthesis of 6-chloropyridazine-3-carboxylic acid

To a mechanically stirred solution of 3-chloro-6-methylpyridazine (155.6 mmol) in 140 mL of concentrated sulfuric acid, finely powdered potassium dichromate (55.40 g) was added slowly, the temperature being kept below 50° C. When the addition was complete, stirring was continued for another 4 hours at 50° C. The viscous, dark green liquid was then cooled and crushed ice was added cautiously. The reaction mixture was extracted with ethyl acetate (6×400 mL). The ethyl acetate extracts were combined, dried over anhydrous Na₂SO₄. The solvent was concentrated in vacuo to yield slightly red colored 6-chloropyridazine-3-carboxylic acid (106.6 mmol). This material was used for next reaction without further purification. Yield 69%. m.p. 145° C. (dec). ¹H NMR (300 MHz, DMSO-d₆) δ 13.1, 8.20, 8.05.

Preparation 3 Synthesis of 6-chloropyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

To a solution of 6-chloropyridazine-3-carboxylic acid (15.8 mmol) in dichloromethane (95 mL) was added diisopropylethylamine (46.7 mmol), 1-hydroxybenzotriazole monohydrate (23.7 mmol) and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (23.7 mmol) under nitrogen atmosphere at ambient temperature. The resulting mixture was stirred for 15 minutes and 2-cyclopropylethylamine (20.2 mmol) was added. After stirring for 36 hours at ambient temperature, the reaction mixture was diluted with dichloromethane (100 mL), then washed with water and dried over anhydrous Na₂SO₄. The solvent was removed in vacuo. Purification via column chromatography (30% ethyl acetate in hexanes) afforded the title compound (8.70 mmol). Yield 55%.

Preparation 4 Synthesis of 6-chloropyridazine-3-carboxylic acid (3-methylbutyl)amide

The mixture of 6-oxo-1,6-dihydropyridazine-3-carboxylic acid monohydrate (3.16 g; 20.0 mmol), dimethylformamide (0.5 mL) and thionyl chloride (5-7 mL) in chloroform (70 mL) was kept at 50-60° C. overnight. The reaction mixture was evaporated in vacuo to dryness. The solid residue was dissolved in dichloromethane (70 mL) and added dropwise to the mixture of 3-methylbutylamine (30 mmol, 2.7 mL) and triethylamine (5 mL) in dichloromethane (150 mL) at ambient temperature. The mixture was stirred for 30 min, washed sequentially with 10% HCl solution, saturated NaHCO₃ and water, and then dried over MgSO₄. The final compound was isolated by recrystallization from ether-hexanes (5:1) (19.76 mmol). Yield: 98%.

Preparation 5 Synthesis of [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethyl-phenyl)methanone

A. To a stirred solution of 1-Boc-piperazine (1.96 g, 10.5 mmol) in dichloromethane (50 mL) was added 2-trifluoromethylbenzoyl chloride (2.09 g, 10.0 mmol) as a dichloromethane solution in the presence of triethylamine (3 mL) at 0° C. The resulting mixture was stirred at ambient temperature for 18 hours and then quenched with water (25 mL). The organic phase was washed with water, saturated NaCl, dried over MgSO₄ and then concentrated in vacuo to afford the desired product as a pall yellow solid used for next step reaction without further purification.

B. A solution of the compound obtained above (10 mmol) in 50 mL of a 1:4 mixture of trifluoroacetic acid and dichloromethane was stirred at ambient temperature for 5 h. After concentration in vacuo the residue was dissolved in dichloromethane (100 mL) and washed sequentially with 1 N NaOH (10 mL), water, saturated NaCl, and then dried over MgSO₄, filtered and concentrated in vacuo to yield piperazin-1-yl-(2-trifluoromethylphenyl)methanone as a light yellow oil. This oil was converted into HCl salt by the addition of 10 mL of 2 N HCl in ether and 100 mL of anhydrous ether to the solution of the compound in 10 mL of dichloromethane. The white solid formed was filtered and dried to yield the HCl salt.

C. A mixture of 3-amino-6-chloropyridazine (0.648 g, 5.00 mmol) and the HCl salt obtained above (7.5 mmol) was heated at 150° C. for 24 hours. To the reaction mixture was added 10 mL of 1 N NaOH and 100 mL of dichloromethane, and the aqueous layer was extracted twice with 100 mL of dichloromethane. The combined organic phase was dried over Na₂SO₄, evaporated to dryness. The crude compound was purified by flash chromatography to give the title compound as a yellow solid.

Preparation 6 Synthesis of (5-fluoro-2-trifluoromethylphenyl)piperazin-1-ylmethanone

A. To a solution 1-benzylpiperazine (4.65 g, 4.58 mL, 26.4 mmol) in dichloromethane (200 mL) was added diisopropylethylamine (4.65 g, 6.2 mL, 36.0 mmol) followed by 5-fluoro-2-(trifluoromethyl)benzoyl chloride (5.43 g, 3.63 mL, 23.9 mmol) at 0° C. The reaction solution was stirred at ambient temperature for 16 hours then diluted with dichloromethane (100 mL) and washed with water (3×100 mL). After the solvent was removed in vacuo, the product (9.81 g, quantitative yield) was obtained as a viscous oil which was used for next step reaction without further purification.

B. The viscous oil was diluted in methanol (100 mL) and Pd/C (981 mg) was added. The mixture was stirred under H₂ for 16 hours. After filtration, the filtrate was concentrated in vacuo to yield 6.98 g (94%) of the product.

Preparation 7 Synthesis of 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

A mixture of piperazine (1.48 g, 17.2 mmol) and 6-chloropyridazine-3-carboxylic acid (2-cyclopropylethyl)amide (1.29 g, 5.73 mmol) in acetonitrile (60 mL) was heated at reflux for 16 hours. After the reaction mixture was cooled, the gummy material was diluted with dichloromethane (50 mL), washed with water (2×20 mL), dried over MgSO₄. After filtration, the filtrate was concentrated in vacuo. The crude material was purified by column chromatography eluting with dichloromethane (100%) then with methanol:dichloromethane (1:9) to obtain 1.18 g (75%) of the product as a solid.

Preparation 8 Synthesis of 2-amino-1-cyclopropylethanol

A. To a stirred mixture of cyclopropanecarboxyaldehyde (1.00 g, 14.3 mmol) and nitromethane (0.765 g, 14.3 mmol) in MeOH at 0° C. was added dropwise a solution of NaOH (0.57 g) in water. The reaction mixture was kept stirring for 1 hour and a white solid was precipitated. Glacial acetic acid (0.807 mL) was then added to this mixture dropwise. The organic layer was extracted with ether (3×7 mL) and dried over MgSO₄ to yield 2-nitro-1-cyclopropylethanol which was used for the next step reaction without further purification.

B. The nitro compound obtained above was dissolved in 4 mL of dry ether and then added dropwise to a stirred slurry of lithium aluminum hydride (0.997 g, 26.3 mmol) in dry ether (30 mL) under refluxing over 1 hour. The reflux was maintained for 2 more hours and then 2-propanol (9 mL) was added and followed by the addition of saturated NaCl solution (3 mL). The mixture was stirred for another 20 minutes and then extracted with mixture of 2-propanol:ether (1:3). 2-Amino-1-cyclopropylethanol was obtained after removal of the solvents and used for next step reaction without further purification.

Preparation 9 Synthesis of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide

To the solution of 6-chloropyridazine-3-carboxylic acid (375 mg, 2.37 mmol) in 5 mL of dioxane was added thionyl chloride (420 mg, 3.56 mmol). The mixture was refluxed for 4 hours and the solvent was removed in vacuo. 2-Amino-1-cyclopropylethanol (479 mg, 4.73 mmol) in 5 mL of dioxane was added to the residue and followed by the addition of triethylamine (0.2 mL). The mixture was stirred at ambient temperature overnight. Water was added to the mixture and then extracted with ethyl acetate. The organic extract was separated, washed with water and brine; dried over Na₂SO₄. The residue after removal of solvent was purified by column chromatography eluted with ethyl acetate:hexane (70:30) to yield 58 mg of the white desired product.

Preparation 10 Synthesis of Piperazine-1-yl-(2-trifluoromethylphenyl)methanone

A. 2-Trifluoromethylbenzoyl chloride was added dropwise to a cooled (0° C.) and stirred solution of 1-Boc-piperazine (0.100 mol) and triethylamine (0.12 mol) in dichloromethane (250 mL) over 15 minutes. The resulting mixture was stirred at ambient temperature for 6 hours. Water (100 mL) was then added to the mixture and the aqueous phase was extracted with dichloromethane (2×100 mL), the combined organic phase was washed with water and brine; dried over Na₂SO₄ and then concentrated in vacuo to afford the product in quantitative yield.

B. A solution of 4-(2-trifluoromethylbenzoylpiperazine-1-carboxylic acid t-butyl ester obtained above (10 mmol) in a mixture of trifluoroacetic acid and dichloromethane (1:4, 50 mL) was stirred at ambient temperature for 5 hours. After concentration in vacuo, the residue was dissolved in dichloromethane (100 mL) and washed sequentially with saturated sodium bicarbonate, water, and brine; dried over anhydrous Na₂SO₄ and concentrated to give piperazine-1-yl-(2-trifluoromethylphenyl)-methanone in 97% yield.

Preparation 11 Synthesis of 6-piperazin-1-ylpyridazine-3-carboxylic acid (3-methylbutyl)amide

A solution of 6-chloropyridazine-3-carboxylic acid (3-methylbutyl)amide (2.52 g, 11.0 mmol) and piperazine (2.83 g, 32.8 mmol) in acetonitrile (30 mL) was heated to refluxed for 2 hours. The solvent was removed by evaporation, the residue was dissolved in water (50 ml) and extracted with dichloromethane (3×100 mL). The organic extract was dried over anhydrous Na₂SO₄ and then evaporated. The residue was passed through a pad of silica gel and concentrated to give 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-methylbutyl)amide (2.68 g, 88% yield). MS (ES+) m/z 278 (M+1).

Preparation 12 Synthesis of 6-piperazin-1-ylpyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

A solution of 6-chloropyridazine-3-carboxylic acid (2-cyclopropylethyl)amide (7.8 g, 34 mmol) and piperazine (8.93 g, 103 mmol) in acetonitrile (100 mL) was heated to refluxed for 2 hours. The solvent was removed by evaporation and the residue was dissolved in water (100 mL). The aqueous solution was extracted with dichloromethane (5×100 mL) and the organic extract was dried over anhydrous Na₂SO₄, filtered through a pad of silica gel and concentrated to give 6-piperazin-1-ylpyridazine-3-carboxylic acid (2-cyclopropylethyl)amide (8.2 g, 88%). ¹H NMR (300 MHz, CDCl₃) δ 7.90-7.87, 6.89, 3.78-3.50, 3.12-2.90, 1.77-1.49, 0.83-0.60, 0.51-0.36, 0.15-0.01.

Preparation 13 Synthesis of 6-chloropyridazine-3-carboxylic acid [2-(3-fluorophenyl)ethyl]amide

To a solution of 6-chloropyridazine-3-carboxylic acid (0.31 g, 1.94 mmol) in dichloromethane (15.5 mL) was added diisopropylethylamine (0.73 mL, 4.19 mmol), followed by 1-hydroxybenzotriazole monohydrate (0.28 g, 2.1 mmol) and 1-(3-dimethylamino)propyl-3-ethylcarbodiimide (0.37 mL, 2.1 mmol). The resulting mixture was stirred for 15 minutes, followed by the addition of 3-fluorophenethylamine (0.28 mL, 2.1 mmol). After stirring for 27 hours at ambient temperature, the reaction mixture was diluted with dichloromethane (200 mL), washed with water (4×25 mL), dried over Na₂SO₄ and concentrated in vacuo. Purification by column chromatography eluted with dichloromethane: ethyl acetate (2:1) afforded the product as a white powder (0.205 g). ¹H NMR (400 MHz, CDCl₃) δ 8.26, 8.12, 7.67, 7.28-7.23, 6.95-6.89, 3.80-3.75, 2.95.

Preparation 14 Synthesis of (E)-2-trifluoromethylcyclopropanecarboxylic acid

A. To a stirred solution of trimethylsulfoxonium iodide (4.85 g, 22.0 mmol) in DMSO (20 mL) under nitrogen at 25-30° C. was added a dispersion of sodium hydride in mineral oil (0.88 g, 22 mmol) in portions. Upon completion of hydrogen evolution (30 minutes), a solution of ethyl 4,4,4-trifluorocrotonate (3.36 g, 3 mL, 20 mmol) in DMSO (10 mL) was added dropwise so that the temperature did not exceed 35° C. The resulting mixture was stirred at 25-30° C. for 30 minutes and then at 55-60° C. for 1 hour. The mixture was poured into 150 mL of aqueous solution of ammonium chloride (4 g). The solution was extracted with ether and ethereal extract was dried over Na₂SO₄ and concentrated to give a crude product.

B. To a solution of the crude product obtained above was added tetrahydrofuran (75 mL), water (38 mL) and lithium hydroxide (3.36 g, 80 mmol). The mixture was stirred and heated to 80° C. for 5.5 hours and then evaporated to remove tetrahydrofuran. The aqueous layer was extracted with hexanes (2×30 mL), acidified with concentrated HCl and then extracted with dichloromethane (3×100 mL). The organic layer was dried over Na₂SO₄. Removal of the solvent afforded 2-trifluoromethylcyclopropane-carboxylic acid (1.53 g).

Preparation 15 Synthesis of 6-chloropyridazine-3-carboxylic acid pentylamide

To a flask containing 6-chloropyridazine-3-carboxylic acid (375 mg, 2.37 mmol) in dioxane (5 mL) was added thionyl chloride (420 mg, 0.26 mL, 3.56 mmol). The brown mixture was refluxed for 6 hours under nitrogen with stirring. After cooling to ambient temperature, the solvent was removed by rotary evaporator. The gummy black material was diluted with dioxane (5 mL) and the resulting solution was cooled in an ice-water bath. To the cooled solution was added amyl amine (410 mg, 0.55 mL, 4.74 mmol). The resulting black reaction solution was stirred at ambient temperature for 16 hours under nitrogen. The solvent was removed in vacuo and the residue was dissolved in dichloromethane (25 mL). The solution was washed with water (2×10 mL) and the organic layer was dried over MgSO₄, filtered-off the solid and concentrated to afford a gummy material which was purified by column chromatography eluted with dichloromethane to yield 310 mg (57%) of the product as a colourless solid. m.p. 98-101° C. ¹H NMR (300 MHz, CDCl₃) δ 8.28, 8.05, 7.68, 3.51, 169-1.63, 0.90. MS (ES+) m/z 228 (M+1).

Preparation 16 Synthesis of 3-cyclopropylpropylamine

A. p-Toluenesulfonyl chloride (7.20 g, 37.8 mmol) was added to a cooled (0° C.) solution of 2-cyclopropylethanol (4.00 g, 46.4 mmol) in pyridine (10 mL) and dichloromethane (60 mL). The reaction mixture was stirred at ambient temperature overnight, then diluted with ether (200 mL) and washed sequentially with water, 10% HCl, water and brine and then dried over anhydrous Na₂SO₄. Toluene-4-sulfonic acid 2-cyclopropylethyl ester (8.1 g, 89%) was obtained after removal of solvent and used for next step reaction without further purification.

B. A mixture of toluene-4-sulfonic acid 2-cyclopropylethyl ester (8.1 g, 33.7 mmol), sodium cyanide (5.0 g, 102 mmol) and tetrabutylammonium iodide (0.5 g) in DMF (30 mL) was heated at 90° C. overnight. The reaction mixture was then cooled to ambient temperature, diluted with ether (200 mL), washed with water and brine, and dried over anhydrous Na₂SO₄. 3-Cyclopropylpropionitrile (3.2 g, 99%) was obtained after removal of solvent.

C. Concentrated sulfuric acid (2.73 mL) was added drop wise to a vigorously stirred ethereal solution of lithium aluminum hydride (3.792 g, 99.43 mmol) in 40 mL of ether at 0° C. The reaction mixture was then warmed to ambient temperature and stirred for 1 hour. A solution of 3-cyclopropylpropionitrile (3.085 g, 32.47 mmol) in ether (10 mL) was added drop wise. The resulting mixture was heated at reflux for 2 hours, then cooled to 0° C., and subsequently slowly quenched with water. A solution of NaOH (2 g in 18 mL of H₂O) was added and organic phase was decanted from the resulting aluminum hydroxide precipitate, which was washed with ether (3×20 mL). All ethereal portions were combined, and the solvent was distilled off and 3-cyclopropylproylamine was obtained as a light yellow liquid (2.01 g, 62.5%).

Preparation 17 Synthesis of 6-(3,5-dimethyl-piperazin-1-yl)pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

To a solution of 6-chloropyridazine-3-carboxylic acid (2-cyclopropylethyl)amide (0.57 g, 2.52 mmol) and Bu₄NBr (0.16 g, 0.50 mmol) in dioxane (20 mL) was added 1,8-diazabicylco[5.4.0]undec-7-ene (DBU) (0.75 mL, 0.77 g, 5.04 mmol). The brown reaction mixture was heated at reflux for 16 hours, then cooled to ambient temperature. The solvent was removed in vacuo. The crude material was diluted with ethyl acetate (50 mL). The solution was washed with water (3×20 mL), dried over MgSO₄. After filtration, the solvent of the filtrate was removed in vacuo. The product was isolated as a brown gummy material (0.72 g, 74%) that was directly used for the next step without further purification.

Preparation 18 Synthesis of 6-[1,4]diazepan-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

A. A mixture of 6-chloropyridazine-3-carboxylic acid (2-cyclopropylethyl)amide (0.15 g, 0.665 mmol), [1,4]diazepane-1-carboxylic acid tert-butyl ester (0.133 g, 0.665 mmol) and triethylamine (0.093 mL, 0.665 mmol) was heated to reflux in toluene for 18 h. The solvent was removed in vacuo, and the residue was purified by flash column chromatography to yield the product (0.226 g, 87%) which was used for the next step reaction without further purification.

B. The product obtained above was dissolved in a 2:1 mixture of dichloromethane/trifluoroacetic acid, and the mixture was stirred for 15 minutes. The solvent was then removed in vacuo. The residue was diluted with dichloromethane, and the resulting solution was washed with 10% aqueous sodium hydroxide solution, dried and concentrated to yield 6-[1,4]diazepan-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide.

Preparation 19 Synthesis of 6-chloropyridazine-3-carboxylic acid (2-cyclobutylethyl)amide

A. To a solution of cyclobutanemethanol (4.00 g, 46.4 mmol) in dichloromethane (60 mL) was added pyridine (10 mL), followed by the addition of p-toluenesulfaryl chloride (7.20 g, 37.8 mmol) at 0° C. The reaction mixture was stirred for 23 h at ambient temperature, and then diluted with diethyl ether (350 mL), washed sequentially with water, 1% aqueous HCl solution, water and brine. The organic layer was dried over Na₂SO₄ and concentrated in vacuo to give the product (9.00 g, 80.7%).

B. To a solution of toluene-4-sulfonic acid cyclobutylmethyl ester (9.00 g, 37.5 mmol) in DMF (34 mL) was added sodium cyanide (5.62 g, 114.6 mmol) and tetra-n-butylammonium iodide (0.56 g, 1.41 mmol). The reaction mixture was stirred at 90 to 95° C. for 6.5 h. After cooled down to ambient temperature, the reaction mixture was diluted with diethyl ether (450 mL), washed with water and brine. The organic layer was dried over Na₂SO₄ and concentrated at atmosphere pressure to give a product (3.50 g).

C. Concentrated sulfuric acid (1.71 mL, 32.6 mmol) was added dropwise to a vigorously stirred solution of lithium aluminum hydride (2.47 g, 65.1 mmol) in 65 mL of ether at 0° C. The reaction mixture was warmed to ambient temperature and stirred for 1 h, and a solution of cyclobutylacetonitrile (2 g, 21.03 mmol) in 9 mL of ether was added dropwise. The resulting mixture was heated at reflux for 3.5 h and then stirred at ambient temperature for 21 h. The reaction mixture was cooled to 0° C., and slowly quenched with water (16 mL). A solution of sodium hydroxide (7.85 g) in water (69 mL) was added, and the organic phase was decanted from the resulting aluminum hydroxide precipitate, which was rinsed with three 50-mL portions of ether. All ethereal portions were combined, and the solvent was distilled off to leave of 2-cyclobutylethylamine as a colorless liquid (1.9 g, 91%).

D. To a 100-mL round bottom flask, 6-oxo-1,6-dihydropyridazine-3-carboxylic acid monohydrate (0.64 g, 3.6 mmol), chloroform (14 mL), dimethylformamide (0.1 mL) and thionyl chloride (1.2 mL) were added. The reaction mixture was stirred at 60° C. for 16 h. The reaction mixture was evaporated in vacuo to dryness. The solid residue was dissolved in dichloromethane (13 mL) and added dropwise to the mixture of cyclobutylethylamine (0.47 g, 4.74 mmol) and triethylamine (0.8 mL) in dichloromethane (25 mL) at ambient temperature. After stirred for 1 h, the reaction mixture was diluted with dichloromethane (100 mL) and washed sequentially with 10% aqueous HCl solution, saturated NaHCO₃ and water. The organic layer was dried over Na₂SO₄ and evaporated in vacuum. Purification by column chromatography (silica gel, hexane/EtOAc (2:1)) afforded the product as a white powder (0.572 g, 59%). ¹H NMR (300 MHz, CDCl₃) δ 8.25, 7.97, 7.65, 3.42, 2.36, 2.08, 1.91-1.59.

Preparation 20 Synthesis of 3-cyclobutylpropylamine

A. A solution of trimethylphosphine in toluene (1 M, 60 mL, 60 mmol) at 0° C. under nitrogen was diluted with toluene (30 mL) and tetrahydrofuran (30 mL). Iodoacetonitrile (4.2 mL, 9.69 g, 58 mmol) was then added dropwise while stirring vigorously, whereby a colorless solid precipitated. When the addition was finished, the ice-bath was removed and stirring was continued at ambient temperature for 51 h. The mixture was filtered, and the solid was washed with toluene and dried under reduced pressure. Recrystallization from acetonitrile (37.5 mL) to give the compound as colorless crystals (9.89 g, yield: 70%).

B. To a mixture of cyclobutanemethanol (0.861 g, 10 mmol) and (cyanomethyl)-trimethylphosphonium iodide (6.20 g, 25.5 mmol) were added propionitrile (20 mL) and diisopropylethylamine (5.5 mL, 32 mmol), and the mixture was stirred at 97° C. for 48 h. Water (1 mL, 55.5 mmol) was added, and stirring at 97° C. was continued for another 18 h. Water (125 mL) and concentrated hydrochloric acid (5 mL, 60 mmol) were added, and the mixture was extracted with dichloromethane (3×100 mL). The combined extracts were washed once with brine, dried with magnesium sulfate, and concentrated at atmosphere pressure to give the product (1.09 g).

C. Concentrated sulfuric acid (3.15 mL, 60.05 mmol) was added dropwise to a vigorously stirred solution of lithium aluminum hydride (4.35 g, 113.8 mmol) in 114 mL of ethyl ether at 0° C. The reaction mixture was warmed to ambient temperature and stirred for 1 h, and a solution of cyclobutylpropionitrile (1.09 g, 10 mmol) in 15 mL of ether was added dropwise. The resulting mixture was heated at reflux for 2 h and then stirred at ambient temperature for 48 h. The reaction mixture was cooled to 0° C., and slowly quenched with water (12 mL). A solution of sodium hydroxide (5.89 g) in water (52 mL) was added, and the organic phase was decanted from the resulting aluminum hydroxide precipitate, which was rinsed with three 50-mL portions of ether. All ethereal portions were combined, and the solvent was distilled off to leave 0.36 g (32%) of 2-cyclobutylpropylamine as a colorless liquid.

Preparation 21 Synthesis of 6-piperazin-1-ylpyridazine-3-carboxylic acid (2-cyclobutylethyl)amide

To a solution of 6-chloropyridazine-3-carboxylic acid (2-cyclobutylethyl)-amide (1.2 g, 5.00 mmol) in acetonitrile (40 mL) was added piperazine (1.29 g, 15.00 mmol). The reaction mixture was heated to reflux overnight. The mixture was evaporated and the solid residue was taken in ethyl acetate (100 mL) and water (100 mL). The organic layer was separated and the aqueous layer was extracted with ethyl acetate (2×100 mL). The combined ethyl acetates were dried over Na₂SO₄ and concentrated in vacuo to give the title compound as yellow solid (1.14 g, 78.4% yield).

Preparation 22 Synthesis of 2,2-(dimethylcyclopropyl)methylamine

Lithium aluminum hydride (7.77 g, 0.194 mmol) was added to a solution of 2,2-dimethylcyclopropanecarboxamide (10.0 g, 88.3 mmol) in THF (200 mL) at 0° C. The reaction mixture was heated to reflux for 5 h, then cooled to 0° C., quenched with water, and extracted with diethyl ether. The combined ether layer was dried over anhydrous Na₂SO₄, and distilled to yield the title compound in 36% yield (3.2 g). b.p. 94-96° C. ¹H NMR (300 MHz, CDCl₃) δ 2.68-2.53, 1.13, 1.03, 1.00, 0.70-0.61, 0.38-0.34, −0.02-−0.05.

Preparation 23 Synthesis of 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid

A. To a methanol solution of 6-oxo-1,6-dihydropyridazine-3-carboxylic acid monohydrate (5.00 g, 31.6 mmol) was added thionyl chloride (0.36 mL, 0.59 g, 4.94 mmol). The reaction mixture was heated to reflux at 80° C. for 16 h. The product crystallized after the reaction mixture was cooled down to ambient temperature. The crystals were collected and washed with methanol and the mother liquor was concentrated and crystallized again. The total amount of product isolated was 4.954 g (100% yield).

B. A mixture of 6-hydroxypyridazine-3-carboxylic acid methyl ester obtained above and phosphorous oxychloride were carefully heated to reflux temperature and maintained there for 2.5 h. The reaction mixture was then cooled and evaporated in vacuo to remove excess phosphorylchloride, and the residue was then poured into ice water. The precipitate was collected by filtration, washed with saturated NaHCO₃ and water, and dried under vacuum to yield the product as a yellow solid (4.359 g, 79% yield).

C. To a solution of 6-chloropyridazine-3-carboxylic acid methyl ester obtained above (4.359 g, 25.3 mmol) in dioxane (145 mL) was treated with 1-(2-trifluoromethyl-benzoyl)piperazine hydrochloric acid salt (7.80 g, 26.5 mmol) in the presence of K₂CO₃ (10.14 g, 73.4 mmol) and tetra-n-butylammonium iodide (0.071 g, 0.192 mmol). The reaction mixture was heated to reflux for 24 h and evaporated to remove dioxane. The residue was purified by column chromatography to afford the desired product (8.666 g, 87% yield).

D. To a solution of 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid methyl ester (4.436 g, 11.25 mmol) in tetrahydrofuran (50 mL) and water (25 mL) was added lithium hydroxide monohydrate (2.30 g, 54.81 mmol). The reaction mixture was stirred at ambient temperature for 23 h and the pH of the solution was adjusted to 3 with concentrate hydrochloric acid (5.3 mL) at 0° C. The mixture was concentrated. Ethyl acetate (100 mL) was added to the residue and the product was precipited. The solid was collected by filtration, washed with ethyl acetate and dried in vacuo to afford the title compound (3.60 g). The aqueous layer was extracted with ethyl acetate, dried over Na₂SO₄ and concentrated to give the second portion of title compound (0.463 g). The total amount of product was 4.063 g (95% yield).

Preparation 24 Synthesis of 6-piperazin-1-ylpyridazine-3-carboxylic acid pent-4-enylamide

A. To a solution of 4-penten-1-ol (4.8 mL, 4.00 g, 46.4 mmol) in dichloromethane (60 mL) was added pyridine (10 mL), followed by the addition of p-toluenesulfuryl chloride (7.2 g, 37.8 mmol) at 0° C. The reaction mixture was stirred for 21 h at ambient temperature. The reaction mixture was then diluted with diethyl ether (350 mL), washed sequentially with water, 1% HCl, water and brine. The organic layer was dried over Na₂SO₄ and concentrated to affors the product in 93% yield (8.48 g) which was used for the next step reaction without further purification.

B. To a solution of toluene-4-sulfonic acid pent-4-enyl ester obtained above (3.42 g, 14.3 mmol) in THF (55 mL) was added ammonium hydroxide (ammonia content 28.0-30.0%) (100 mL, 1532.6 mmol). The reaction mixture was stirred at ambient temperature for 5 days. The reaction mixture was extracted with diethyl ether. The combined ether solution was dried over Na₂SO₄ and distilled under atmosphere at 50° C. to yield a THF solution of pent-4-enylamine, which was used for next step reaction without further purification.

C. 6-Oxo-1,6-dihydropyridazine-3-carboxylic acid monohydrate (1.60 g, 10.1 mmol), chloroform (36 mL), dimethylformamide (0.25 mL) and thionyl chloride (3.05 mL) were added to a 100-mL round bottom flask. The reaction mixture was stirred at 69° C. for 43 h and then evaporated to dryness. The solid residue was dissolved in dichloromethane and the solution was added dropwise to the mixture of pent-4-enylamine in THF prepared above and triethylamine at ambient temperature. After stirred for 1 h, the reaction mixture was diluted with dichloromethane and washed with 10% HCl, saturated NaHCO₃ and water. The organic layer was dried over Na₂SO₄ and evaporated in vacuum. Purification by column chromatography afforded the product as a white powder (1.08 g, 61.6% yield).

D. To a solution of 6-chloropyridazine-3-carboxylic acid pent-4-enylamide synthesized above (1.08 g, 4.79 mmol) in acetonitrile (39 mL) was added piperazine (1.25 g, 14.5 mmol). The reaction mixture was heated to reflux overnight (TLC indicated the reaction was complete). The mixture was evaporated and the solid residue was dissolved in a mixture of ethyl acetate (100 mL) and water (100 mL). The organic layer was separated and the aqueous layer was extracted with ethyl acetate. The combined ethyl acetate layer were dried over Na₂SO₄ and concentrated to yield the title compound as a yellow solid (1.169 g, 88.6% yield).

The syntheses of compounds of this invention are illustrated by, but not limited to the following examples.

Example 1 Synthesis of 4-methylpentanoic acid {6-[4-(2-trifluoromethylbenzoyl)-piperazin-1-yl]pyridazin-3-yl}amide

To a stirred solution of [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethyl-phenyl)methanone (0.226 g, 0.645 mmol) in tetrahydrofuran (10.0 mL) was added 4-methylpentanoic acid (0.500 g, 4.30 mmol) followed by (3-dimethylaminopropyl)-ethyl carbodiimide (1.0 mL). The mixture was stirred at ambient temperature overnight. Water was added and the mixture was extracted with ethyl acetate. The combined organic layer was dried with Na₂SO₄, concentrated, and the residue was dissolved again in a small amount of ethyl acetate. The solid, which precipitated by dropwise addition of hexane was filtered off and dried in vacuum to give the title product (0.070 g) as a white solid in 24% yield. ¹H NMR (300 MHz, CDCl₃) δ 9.15, 8.36, 7.74, 7.63, 7.56, 7.36, 7.05, 4.03-3.98, 3.93-3.89, 3.69-3.62, 3.55-3.53, 3.33-3.31, 2.51, 1.63-1.61, 0.91.

Example 1.1 4-Phenyl-N-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}butyramide

Following the procedure of Example 1, making variations only as required to use 4-phenylbutyric acid in place of 4-methylpentanoic acid to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (9% yield). ¹H NMR (300 MHz, CDCl₃) δ 9.13, 8.36, 7.74, 7.62, 7.56, 7.36, 7.28-7.25, 7.19-7.16, 7.05, 4.03-3.98, 3.93-3.88, 3.69-3.60, 3.54-3.52, 3.33-3.31, 2.70, 2.52, 2.06.

Example 1.2 4-(4-methoxyphenyl)-n-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}butyramide

Following the procedure of Example 1, making variations only as required to use 4-(4-methoxyphenyl)butyric acid in place of 4-methylpentanoic acid to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)-methanone, the title compound was obtained as a white powder (20% yield). ¹H NMR (300 MHz, CDCl₃) δ 9.14, 8.29, 7.67, 7.55, 7.49, 7.30, 7.01, 6.98, 6.73, 3.95-3.91, 3.86-3.81, 3.70, 3.61-3.55, 3.48-3.45, 3.26-3.24, 2.57, 2.45, 1.96.

Example 2 Synthesis of 2-benzyloxy-n-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]-pyridazin-3-yl}acetamide

To a stirred solution of [4-(6-aminopyridazin-3-yl)piperazin-1-yl]-(2-trifluoromethylphenyl)methanone (1.30 g, 3.7 mmol) in dichloromethane (60 mL) was added diisopropylethylamine (1.5 g), followed by 1-hydroxybenzotriazole monohydrate (1.1 g) and N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide (2 mL). The resulting mixture was stirred for 15 minutes and then benzyloxyacetic acid (1.2 mL) was added. After stirring for 2 hours the reaction mixture was washed with 10% HCl, 1 N NaOH and water, dried over anhydrous Na₂SO₄ and concentrated in vacuo to afford the final amide as a dark yellow oil. The oil was purified by column chromatography (dichloromethane:MeOH=98:2) providing 1.64 g of pure final compound as a white solid in 89% yield. ¹H NMR (300 MHz, CDCl₃) δ 9.12, 8.29, 7.72, 7.63-7.49, 7.35-7.33, 6.99, 4.65, 4.10, 4.05-3.83, 3.66-3.54, 3.33-3.29. MS (ES+) m/z 500.2 (M+1).

Example 2.1 4-cyclohexyl-N-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}butyramide

Following the procedure of Example 2, making variations only as required to use 4-cyclohexylbutyric acid in place of benzyloxyacetic acid to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (18% yield). ¹H NMR (300 MHz, CDCl₃) δ 9.04, 8.32, 7.68, 7.56, 7.49, 7.30, 7.04-7.00, 3.99-3.23, 2.40, 1.89-1.83, 1.69-0.84.

Example 2.2 2-ethoxy-N-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}-acetamide

Following the procedure of Example 2, making variations only as required to use ethoxyacetic acid in place of benzyloxyacetic acid to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a yellow solid (67% yield). ¹H NMR (300 MHz, CDCl₃) δ 9.18, 8.35, 7.75, 7.63, 7.56, 7.37, 7.04, 4.08, 4.04-3.88, 3.70-3.64, 3.60-3.58, 3.35-3.33, 1.31. MS (ES+) m/z 438.4 (M+1).

Example 2.3 2-Cyclopropylmethoxy-N-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]-pyridazin-3-yl}acetamide

Following the procedure of Example 2, making variations only as required to use cyclopropylmethoxyacetic acid in place of benzyloxyacetic acid to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (41% yield). ¹H NMR (300 MHz, CDCl₃) δ 9.17, 8.32, 7.72, 7.61, 7.54, 7.35, 4.10, 4.01-3.88, 3.69-3.61, 3.57-3.55, 3.43, 3.33-3.30, 1.14-1.08, 0.61-0.57, 0.27-0.24. MS (ES+) m/z 464.5 (M+1).

Example 2.4 2-(2-methoxyethoxy)-N-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]-pyridazin-3-yl}acetamide

Following the procedure of Example 2, making variations only as required to use (2-methoxyethoxy)acetic acid in place of benzyloxyacetic acid to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (72% yield). ¹H NMR (300 MHz, CDCl₃) δ 9.53, 8.34, 7.74, 7.63, 7.56, 7.34, 7.02, 4.16, 4.04-3.89, 3.80-3.77, 3.69-3.65, 3.63-3.61, 3.59-3.56, 3.46, 3.34-3.32. MS (ES+) m/z 468.3 (M+1).

Example 2.5 2,2,3,3-tetramethylcyclopropanecarboxylic acid {6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}amide

Following the procedure of Example 2, making variations only as required to use 2,2,3,3-tetramethylcyclopropanecarboxylic acid in place of benzyloxyacetic acid to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)-methanone, the title compound was obtained as a white powder (48% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.77, 8.28, 7.72, 7.60, 7.53, 7.34, 6.99, 4.01-3.85, 3.63-3.60, 3.52-3.45, 3.31-3.27, 1.78-1.74, 1.28, 1.20. MS (ES+) m/z 476.3 (M+1).

Example 2.6 Cyclopropanecarboxylic acid {6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}amide

Following the procedure of Example 2, making variations only as required to use cyclopropanecarboxylic acid in place of benzyloxyacetic acid to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (32% yield). ¹H NMR (300 MHz, CDCl₃) δ 10.07, 8.40, 7.72, 7.61, 7.53, 7.34, 7.03, 4.02-3.82, 3.67-3.55, 3.49-3.46, 3.30-3.27, 2.09-2.01, 1.09-1.04, 0.88-0.82. MS (ES+) m/z 420.2 (M+1).

Example 2.7 1-trifluoromethylcyclopropanecarboxylic acid {6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}amide

Following the procedure of Example 2, making variations only as required to use 1-trifluoromethylcyclopropanecarboxylic acid in place of benzyloxyacetic acid to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)-methanone, the title compound was obtained as a white powder (16% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.62, 8.18, 7.74, 7.63, 7.56, 7.34, 7.01, 4.03-3.89, 3.71-3.62, 3.60-3.58, 3.34-3.32, 1.54-1.52, 1.39-1.36. MS (ES+) m/z 487.9 (M+1).

Example 2.8 N-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}-2-(3,3,3-trifluoropropoxy)acetamide

Following the procedure of Example 2, making variations only as required to use (3,3,3-trifluoropropoxy)acetic acid in place of benzyloxyacetic acid to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (50% yield). ¹H NMR (300 MHz, CDCl₃) δ 9.03, 8.32, 7.75, 7.63, 7.56, 7.37, 7.03, 4.13, 4.03-3.98, 3.94-3.89, 3.84, 3.71-3.63, 3.60-3.58, 3.35-3.32, 2.56-2.48. MS (ES+) m/z 506.5 (M+1).

Example 2.9 3-methoxy-N-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}propionamide

Following the procedure of Example 2, making variations only as required to use 3-methoxypropionic acid in place of benzyloxyacetic acid to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (11% yield). ¹H NMR (300 MHz, CDCl₃) δ 9.44, 8.31, 7.74, 7.63, 7.55, 7.36, 7.02, 4.02-3.98, 3.94-3.89, 3.73, 3.70-3.61, 3.57-3.54, 3.43, 3.33-3.31, 2.73. MS (ES+) m/z 438.1 (M+1).

Example 2.10 3-phenoxy-N-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}propionamide

Following the procedure of Example 2, making variations only as required to use 3-phenoxypropionic acid in place of benzyloxyacetic acid to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (52% yield). ¹H NMR (300 MHz, CDCl₃) δ 10.08, 8.40, 7.74, 7.61, 7.55, 7.34, 7.26-7.22, 7.05, 6.93, 6.88, 4.34, 4.01-3.96, 3.92-3.86, 3.68-3.60, 3.55-3.53, 3.29-3.27, 3.08. MS (ES+) m/z 500.3 (M+1).

Example 2.11 3-(4-fluorophenyl)-N-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}propionamide

Following the procedure of Example 2, making variations only as required to use 3-(4-fluorophenyl)propionic acid in place of benzyloxyacetic acid to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a white solid (58.5% yield). ¹H NMR (300 MHz, CDCl₃) δ 10.33, 8.40, 7.78, 7.67, 7.60, 7.36, 7.14, 7.08, 6.85, 3.90, 3.51, 3.20, 3.02, 2.92. MS (ES+) m/z 502.7 (M+1).

Example 2.12 2-butoxy-N-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}acetamide

Following the procedure of Example 2, making variations only as required to use butoxyacetic acid in place of benzyloxyacetic acid to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (40.8% yield). ¹H NMR (300 MHz, CDCl₃) δ 9.19, 8.35, 7.72, 7.55, 7.33, 7.03, 4.05, 3.94, 3.60, 3.31, 1.64, 1.43, 0.93. MS (ES+) m/z 465.6 (M+1).

Example 2.13 2-methyl-1-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-ylcarbamoyl}propylammonium chloride

Following the procedure of Example 2, making variations only as required to use 2-amino-3-methylbutyric acid in place of benzyloxyacetic acid to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone and then treated with HCl, the title compound was obtained as a white powder of HCl salt (48% yield). ¹H NMR (300 MHz, DMSO-d₆) δ 11.53, 8.50, 8.12, 7.84, 7.76, 7.68, 7.62, 7.54, 3.90, 3.36, 3.25, 2.20, 0.98. MS (ES+) m/z 451.2 (M+1).

Example 2.14 5-[1,2]dithiolan-3-yl-pentanoic acid {6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}amide

Following the procedure of Example 2, making variations only as required to use lipoic acid in place of benzyloxyacetic acid to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a white solid (yield 8%). ¹H NMR (300 MHz, CDCl₃) δ 10.11, 8.37, 7.72, 7.61, 7.53, 7.35, 7.04, 4.08-3.84, 3.70-3.57, 3.56-3.46, 3.33-3.30, 3.17-3.02, 2.59, 2.39, 1.84, 1.78-1.56, 1.51-1.37. ¹³C NMR (300 MHz, CDCl₃): 172.52, 167.57, 157.94, 150.00, 134.42, 132.38, 129.45, 127.79, 127.29, 127.14, 126.93, 126.88, 126.82, 121.92, 116.27, 56.34, 46.47, 45.65, 45.33, 41.25, 40.26, 38.49, 37.05, 34.74, 28.85, 25.14. MS (ES+) m/z 540.1 (M+1).

Example 2.15 2-(2-cyclopropylethoxy)-N-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]-pyridazin-3-yl}acetamide

Following the procedure of Example 2, making variations only as required to use 5-(2-cyclopropylethoxy)acetic acid in place of benzyloxyacetic acid to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a white solid (0.056 g, 41% yield). ¹H NMR (300 MHz, CDCl₃) δ 9.15, 8.32, 7.73-7.7, 7.61-7.53, 7.35-7.33, 7.0, 4.07, 3.97-3.89, 3.64, 3.57-3.54, 3.32-3.29, 1.57-1.51, 0.85-0.75, 0.52-0.48, 0.09-0.07. ¹³C NMR (75 MHz, CDCl₃) δ 168.8, 167.5, 158.3, 148.3, 134.4, 132.3, 129.3, 127.7, 127.5, 127.2, 127.1, 126.8, 126.7, 126.3, 125.4, 121.8, 120.9, 115.5, 72.2, 70.2, 46.4, 45.5, 45.1, 41.2, 34.5, 7.8, 4.2. MS (ES+) m/z 478.3 (M+1).

Example 3 Synthesis of 6-[4-(isoxazole-5-carbonyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide

To a stirred solution of 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-methylbutyl)amide (277 mg, 1 mmol) in dichloromethane (15 mL) was added isoxazole-5-carbonyl chloride (1.0 mmol) as a dichloromethane solution in the presence of triethylamine (0.4 mL) at ambient temperature. After 1 hour the mixture was evaporated and the residue was subjected to column chromatography. Final product was isolated as a solid (0.107 g, yield 29%). ¹H NMR (300 MHz, CDCl₃) δ 8.34, 8.05, 7.83, 7.00, 6.86, 3.90-3.84, 3.51-3.45, 1.75-1.62, 1.53-1.46, 0.92. MS (ES+) m/z 373.3 (M+1).

Example 3.1 6-[4-(1-methyl-5- trifluoromethyl-1h-pyrazole-4-carbonyl)piperazin-1-yl]-pyridazine-3-carboxylic acid (3-methylbutyl)amide

Following the procedure of Example 3, making variations only as required to use 1-methyl-5-trifluoromethyl-1H-pyrazole-4-carbonyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-methylbutyl)amide, the title compound was obtained as a white powder (47% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.04, 7.82, 7.54, 6.99, 3.97, 3.90-3.54, 3.51-3.44, 1.75-1.62, 1.53-1.46, 0.92. MS (ES+) m/z 454.3 (M+1).

Example 3.2 6-[4-(4-methylpiperazine-1-carbonyl)piperazin-1-yl]pyridazin E-3-carboxylic acid (3-methylbutyl)amide

Following the procedure of Example 3, making variations only as required to use 4-methylpiperazine-1-carbonyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-methylbutyl)amide, the title compound was obtained as a white powder (79% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.01, 7.83, 6.96, 3.77-3.73, 3.51-3.44, 3.42-3.38, 3.36-3.33, 2.44-2.41, 2.31, 1.75-1.62, 1.48, 0.92. MS (ES+) m/z 404.4 (M+1).

Example 3.3 6-(4-benzoylpiperazin-1-yl)pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 3, making variations only as required to use benzoyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (92% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.04, 7.97, 7.44, 6.98, 3.99-3.62, 3.55, 1.50, 0.80-0.66, 0.48-0.42, 0.11-0.06. MS (ES+) m/z 380.2 (M+1).

Example 3.4 6-[4-(2-ethylbutyryl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 3, making variations only as required to use 2-ethylbutyryl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (71% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.07, 8.00, 7.00, 3.86-3.90, 3.76, 3.68, 3.57, 2.57, 1.70, 1.50-1.55, 0.90, 0.45, 0.10. MS (ES+) m/z 374 (M+1).

Example 3.5 6-(4-cyclohexanecarbonylpiperazin-1-yl)pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 3, making variations only as required to use cyclohexanecarbonyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)-amide, the title compound was obtained as a white solid (58% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.06, 7.99, 6.99, 3.88, 3.79, 3.68, 3.56, 2.50, 1.67-1.84, 1.48-1.60, 1.24-1.34, 0.76, 0.47, 0.10. MS (ES+) m/z 386 (M+1).

Example 3.6 6-[4-(2-trifluoromethoxybenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide

Following the procedure of Example 3, making variations only as required to use 2-trifluoromethoxybenzoyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-methylbutyl)amide, the title compound was obtained as a white solid (83% yield). ¹H NMR (400 MHz, CDCl₃) δ 8.06, 7.85, 7.53-7.32, 7.01, 4.12-3.36, 1.75-1.66, 1.54-1.48, 0.98. MS (ES+) m/z 466.2 (M+1).

Example 3.7 6-[4-(5-chloro-2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide

Following the procedure of Example 3, making variations only as required to use 5-chloro-2-trifluoromethylbenzoyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-methylbutyl)amide, the title compound was obtained as a white solid (80%). m.p. 148-151° C. ¹H NMR (400 MHz, CDCl₃) δ 8.06, 7.85, 7.67, 7.54-7.50, 7.35, 7.01, 4.05-3.34, 1.73-1.46, 0.98. MS (ES+) m/z 484.3 (M+1).

Example 3.8 6-[4-(2-Trifluoromethylbenzoyl)Piperazin-1-yl]Pyridazine-3-Carboxylic Acid (2-Cyclopropylethyl)Amide

Following the procedure of Example 3, making variations only as required to use 2-trifluoromethylbenzoyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (92%). m.p. 95-98° C. ¹H NMR (300 MHz, CDCl₃) δ 8.05, 7.96, 7.74, 7.65-7.52, 7.35, 6.99, 4.08-3.22, 1.55-1.46, 0.80-0.67, 0.48-0.42, 0.10-0.07. ¹³C NMR (75 MHz, CDCl₃) δ 167.6, 162.9, 160.0, 145.4, 134.2, 132.3, 129.5, 127.2, 127.1, 126.9, 121.8, 118.2, 112.5, 46.3, 44.5, 44.4, 41.2, 39.6, 34.5, 8.6, 4.2. MS (ES+) n1/z 448.2 (M+1).

Example 3.9 6-[4-(2-chloro-5-fluorobenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 3, making variations only as required to use 2-chloro-5-fluorobenzoyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (94% yield). m.p. 194-196° C. ¹H NMR (300 MHz, CDCl₃) δ 8.05, 7.96, 7.41-7.37, 7.11-7.03, 7.00, 4.07-3.34, 1.55-1.46, 0.79-0.68, 0.48-0.42, 0.11-0.06. ¹³C NMR (75 MHz, CDCl₃) δ 165.7, 163.0, 160.0, 159.7, 145.5, 136.7, 131.5, 127.1, 125.3, 117.8, 115.2, 112.5, 46.0, 44.8, 44.6, 41.2, 39.6, 34.5, 8.6, 4.2. MS (ES+) m/z 432.2 (M+1).

Example 3.10 6-[4-(3,3,3-trifluoro-2-methyl-2-trifluoromethylpropionyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 3, making variations only as required to use (3,3,3-trifluoro-2-methyl-2-trifluoromethylpropionyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (35% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.02, 7.96, 6.80, 3.91-3.75, 3.58, 1.58-1.48, 0.78-0.63, 0.48-0.43, 0.11-0.04. MS (ES+) m/z 468.2 (M+1).

Example 3.11 6-[4-(2,2-dimethylpropionyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 3, making variations only as required to use 2,2-dimethylpropionyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (64% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.05, 8.01, 6.98, 3.86-3.73, 3.57, 1.57-1.48, 0.79-0.70, 0.52-0.45, 0.16-0.12. MS (ES+) m/z 360.0 (M+1).

Example 3.12 6-[4-(5-Chloro-2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 3, making variations only as required to use 5-chloro-2-trifluoromethylbenzoyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (58% yield). m.p. 164-166° C. ¹H NMR (300 MHz, CDCl₃) δ 8.07, 7.96, 7.69, 7.54, 7.02, 4.07-3.35, 1.52, 0.79-0.68, 0.48-0.43, 0.14-0.08. MS (ES+) m/z 482.1 (M+1).

Example 3.13 6-[4-(5-fluoro-2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 3, making variations only as required to use 5-fluoro-2-trifluoromethylbenzoyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white powder (65% yield). ¹H NMR (400 MHz, CDCl₃) δ 8.05, 7.98, 7.74, 7.27-7.24, 7.09-7.06, 7.00, 4.08-3.96, 3.94-3.68, 3.55, 3.36, 1.50, 0.79-0.69, 0.48-0.42, 0.11-0.09.

Example 3.14 6-[4-(2,6-difluorobenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 3, making variations only as required to use 2,6-difluorobenzoyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white powder (44% yield). ¹H NMR (400 MHz, CDCl₃) δ 8.07, 8.07-7.99, 7.44-7.38, 7.02-6.96, 4.0-3.99, 3.86-3.83, 3.58-3.50, 3.39-3.38, 1.52, 1.15-1.10, 0.77-0.74, 0.49-0.45, 0.11-0.08.

Example 3.15 6-[4-(pyrrolidine-1-carbonyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 3, making variations only as required to use pyrrolidine-1-carbonyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white powder (54% yield). ¹H NMR (400 MHz, CDCl₃) δ 8.04, 7.98, 6.99, 3.79, 3.56, 3.47-3.45, 3.40, 1.87-1.85, 1.52, 0.80-0.72, 0.48-0.46, 0.10-0.09.

Example 3.16 6-[4-(2,5-bis-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 3, making variations only as required to use 2,5-bis-trifluoromethylbenzoyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white powder (50% yield). ¹H NMR (400 MHz, CDCl₃) δ 8.08, 7.99, 7.92-7.9, 7.85-7.84, 7.65, 7.02, 4.13-4.08, 3.95-3.71, 3.57-3.55, 3.38-3.36, 1.57-1.44, 0.8-0.7, 0.48-0.46, 0.16-0.08.

Example 3.17 6-[4-(2,4-bis-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 3, making variations only as required to use 2,4-bis-trifluoromethylbenzoyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white powder (29% yield). ¹H NMR (400 MHz, CDCl₃) δ 8.08, 8.02-7.98, 7.91, 7.54, 7.03, 3.97-3.86, 3.85-3.72, 3.57, 3.36, 1.52, 0.77-0.74, 0.49-0.46, 0.12-0.09.

Example 3.18 6-[4-(2,5-difluorobenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 3, making variations only as required to use 2,5-difluorobenzoyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)-amide, the title compound was obtained as a white powder (53% yield). ¹H NMR (400 MHz, CDCl₃) δ 8.08, 8.0, 7.17-7.11, 7.03, 4.02-3.92, 3.85-3.83, 3.59-3.5, 1.52, 0.74-0.69, 0.46-0.40, 0.09-0.04.

Example 3.19 6-[4-(5-fluoro-2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-cyclopropylpropyl)amide

Following the procedure of Example 3, making variations only as required to use 5-Fluoro-2-trifluoromethylbenzoyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-cyclopropylpropyl)amide, the title compound was obtained as a white powder (28% yield). ¹H NMR (400 MHz, CDCl₃) δ 8.07, 7.89, 7.76, 7.28-7.24, 7.10-7.08, 7.02, 4.06-4.03, 3.90-3.86, 3.82-3.72, 3.51, 3.37, 1.76-1.70, 1.30, 0.70-0.67, 0.44-0.40, 0.03-0.003.

Example 3.20 6-[4-(2-chloro-4-trifluoromethylpyrimidine-5-carbonyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 3, making variations only as required to use 2-chloro-4-trifluoromethylpyrimidine-5-carbonyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white powder (35% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.77, 8.08, 7.97, 7.01, 4.06-3.68, 3.55, 3.39, 1.50, 0.76-0.71, 0.48-0.42, 0.10-0.05.

Example 3.21 6-[4-(2-fluorobenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 3, making variations only as required to use 2-fluorobenzoyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white powder (20.3% yield). ¹H NMR (300 MHz, CDCl₃) δ8.04, 7.98, 7.47-7.40, 7.26-7.21, 7.15-7.09, 6.99, 3.95-3.78, 3.58-3.5, 1.54-1.47, 0.78-0.69, 0.48-0.42, 0.11-0.05.

Example 3.22 6-[4-(3-fluoro-2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 3, making variations only as required to use 3-fluoro-2-trifluoromethylbenzoyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white powder (31% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.05, 7.97, 7.65-7.59, 7.29, 7.12, 6.99, 4.05-3.99, 3.89-3.72, 3.54, 3.35, 1.50, 0.76-0.71, 0.48-0.42, 0.10-0.05.

Example 3.23 6-[4-(4-fluoro-2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-cyclopropylpropyl)amide

Following the procedure of Example 3, making variations only as required to use 4-fluoro-2-trifluoromethylbenzoyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-cyclopropylpropyl)amide, the title compound was obtained as a white powder (49% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.04, 7.87, 7.45-7.3, 6.99, 4.09-3.98, 3.89-3.67, 3.49, 3.33, 1.75-1.66, 1.28, 0.69-0.62, 0.43-0.37, 0.04-0.03.

Example Example 3.24 6-[4-(5-chloro-2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-cyclopropylpropyl)amide

Following the procedure of Example 3, making variations only as required to use 5-chloro-2-trifluoromethylbenzoyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-cyclopropylpropyl)amide, the title compound was obtained as a white solid (73% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.05, 7.86, 7.68-7.65, 7.53-7.5, 7.35, 6.99, 4.05-3.99, 3.89-3.67, 3.52-3.46, 3.37-3.34, 1.75-1.6, 1.31-1.24, 0.71-0.62, 0.43-0.37, 0.02-0.03. ¹³C NMR (75 MHz, CDCl₃) δ 165.9, 162.9, 159.9, 145.4, 138.8, 135.93, 135.9, 129.7, 128.6, 128.4, 121.4, 112.6, 46.3, 44.5, 44.3, 41.3, 39.2, 31.9, 29.5, 10.5, 4.4. MS (ES+) m/z 496.3 (M+1).

Example 3.25 6-[4-(5-fluoro-2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (4-methylpentyl)amide

Following the procedure of Example 3, making variations only as required to use 5-fluoro-2-trifluoromethylbenzoyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (4-methylpentyl)amide, the title compound was obtained as a white solid (10% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.04, 7.86, 7.75-7.71, 7.26-7.22, 7.08-7.04, 6.98, 4.10-3.98, 3.90-3.70, 3.46-3.40, 3.36-3.33, 1.61-1.50, 1.28-1.20, 0.85. ¹³C NMR (75 MHz, CDCl₃) δ 166.0, 162.9, 162.6, 159.9, 145.5, 136.8, 129.7, 127.6, 127.7, 127.2, 125.1, 123.3, 121.4, 116.8, 116.5, 114.9, 114.6, 113.9, 112.5, 46.3, 44.5, 44.3, 41.3, 39.7, 36.0, 27.8, 27.4, 22.5. MS (ES+) m/z 482.4 (M+1).

Example 3.26 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (4-methylpentyl)amide

Following the procedure of Example 3, making variations only as required to use 2-trifluoromethylbenzoyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (4-methylpentyl)amide, the title compound was obtained as a white solid (65.5% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.03, 7.86, 7.74-7.72, 7.62-7.54, 7.36-7.34, 6.98, 4.08-3.98, 3.92-3.65, 3.47-3.4, 3.35-3.31, 1.62-1.53, 1.28-1.21, 0.86. ¹³C NMR (75 MHz, CDCl₃) δ 167.5, 162.9, 159.9, 145.3, 134.2, 132.3, 129.4, 127.0, 126.7, 126.2, 125.4, 121.7, 112.5, 46.3, 44.5, 44.3, 41.2, 39.6, 35.9, 27.7, 27.4, 22.4. MS (ES+) m/z 464.5 (M+1).

Example 3.27 6-[4-(4-fluoro-2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 3, making variations only as required to use 4-fluoro-2-trifluoromethylbenzoyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (83.5% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.05, 7.97, 7.46-7.42, 7.39-7.29, 6.97, 4.07-4.01, 3.89-3.67, 3.58-3.51, 3.36-3.32, 1.53-147, 0.76-0.69, 0.48-0.42, 0.10-0.06. ¹³C NMR (75 MHz, CDCl₃) δ 166.7, 163.9, 162.8, 160.6, 159.9, 145.4, 129.6, 129.5, 127.0, 119.7, 119.4, 114.8, 114.7, 114.4, 114.38, 112.5, 44.4, 44.5, 44.3, 41.3, 39.6, 34.4, 8.6, 4.1. MS (ES+) m/z 466.1 (M+1).

Example 3.28 6-[4-(2-nitrobenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide

Following the procedure of Example 3, making variations only as required to use 2-nitrobenzoyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-methylbutyl)amide, the title compound was obtained as a white solid (72% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.24, 8.07, 7.84, 7.76, 7.63, 7.44, 7.01, 4.12-4.26, 3.75-3.95, 3.50, 3.41, 1.65-1.76, 1.52, 0.94. MS (ES+) m/z 427 (M+1).

Example 3.29 6-[4-(2-chlorobenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide

Following the procedure of Example 3, making variations only as required to use 2-chlorobenzoyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-methylbutyl)amide, the title compound was obtained as a white solid (94% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.05, 7.85, 7.43-7.46, 7.31-7.40, 7.00, 4.04-4.10, 3.75-3.94, 3.34-3.52, 1.65-1.75, 1.52, 0.94. MS (ES+) m/z 416 (M+1).

Example 3.30 6-[4-(2,4-dichlorobenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide

Following the procedure of Example 3, making variations only as required to use 2,4-dichlorobenzoyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-methylbutyl)amide, the title compound was obtained as a white solid (90% yield). 5H NMR (500 MHz, CS(C13) δ 8.07, 7.85, 7.47, 7.35, 7.28, 7.01, 4.02-4.09, 3.75-3.93, 3.33-3.52, 1.65-1.75, 1.52, 0.94. MS (ES+) m/z 450 (M).

Example 3.31 Acetic acid 2-{4-[6-(2-cyclopropylethylcarbamoyl)pyridazin-3-yl]-piperazine-1-carbonyl}phenyl ester

Following the procedure of Example 3, making variations only as required to use acetylsalicyloyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (39% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.06, 8.00, 7.00, 7.47, 7.34-7.29, 7.18, 6.98, 4.00-3.72, 3.60-3.48, 2.28, 1.52, 0.76, 0.48, 0.10. MS (ES+) m/z 438 (M+1).

Example 3.32 6-[4-(5-chloro-2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclobutylethyl)amide

Following the procedure of Example 3, making variations only as required to use 5-chloro-2-(trifluoromethyl)benzoyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-ylpyridazine-3-carboxylic acid (2-cyclobutyl-ethyl)amide, the title compound was obtained as a white powder (71% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.07, 7.81, 7.66, 7.51, 7.34, 3.86-3.66, 3.40-3.34, 2.33, 2.03, 1.86-1.57. ¹³C NMR (75 MHz, CDCl₃) δ 166.0, 162.8, 159.8, 145.5, 138.9, 135.9, 129.8, 128.5, 127.5, 127.3, 125.6, 125.2, 112.7, 46.4, 44.6, 44.5, 41.3, 37.6, 36.5, 33.7, 28.3, 18.6. MS (ES+) m/z 496.5 (M+1).

Example 3.33 6-[4-(5-fluoro-2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclobutylethyl)amide

Following the procedure of Example 3, making variations only as required to use 5-fluoro-2-(trifluoromethyl)benzoyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclobutylethyl)amide, the title compound was obtained as a white powder (71% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.03, 7.83-7.71, 7.20, 7.06, 6.95, 4.01, 3.88-3.67, 3.40-3.28, 2.35, 1.89-1.57. ¹³C NMR (300 MHz, CDCl₃) δ166.0, 162.8, 162.6, 159.9, 145.5, 137.0, 19.7, 127.2, 125.1, 121.5, 116.9, 116.6, 115.0, 114.7, 112.6, 46.4, 44.6, 44.4, 41.3, 37.6, 36.5, 33.7, 28.3, 18.6. MS (ES+) m/z 480.5 (M+1).

Example 3.34 6-[4-(5-chloro-2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid hexylamide

Following the procedure of Example 3, making variations only as required to use 5-chloro-2-(trifluoromethyl)benzyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid hexylamide, the title compound was obtained as a white powder (55% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.07, 7.86, 7.66, 7.51, 7.34, 7.00, 4.00, 3.88-3.66, 3.47-3.33, 1.62-1.53, 1.38-1.27, 0.85. ¹³C NMR (75 MHz, CDCl₃) δ 166.0, 162.9, 159.9, 145.5, 138.9, 135.9, 129.8, 128.5, 127.5, 127.2, 125.6, 125.1, 121.5, 112.7, 46.4, 44.6, 41.3, 39.5, 31.5, 29.5, 26.6, 22.6, 14.0. MS (ES+) m/z 498.2 (M+1).

Example 3.35 6-[4-(5-fluoro-2-trifluoromethylbenzoyl)-[1,4]diazepan-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 3, making variations only as required to use 5-fluoro-2-trifluoromethylbenzoyl chloride in place of isoxazole-5-carbonyl chloride to react with 6-[1,4]diazepan-1-ylpyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (60% yield). ¹H NMR (CDCl₃, 300 MHz) δ 8.07-7.85, 7.71-7.6, 7.23-7.08, 6.94-6.88, 6.34-6.31, 4.24-4.12, 3.98-3.73, 3.67-3.36, 3.29-3.25, 2.19-1.73, 1.53-1.46, 0.81-0.68, 0.48-0.4, 0.11-0.03. ¹³C NMR (CDCl₃, 75 MHz) δ 167.3, 167.2, 165.7, 163.1, 162.9, 162.3, 158.9, 158.4, 144.8, 144.6, 137.1, 129.7-129.2, 127.4, 127.2, 125.0, 121.4, 116.7, 116.6, 116.4, 116.3, 114.9, 114.8, 114.6, 114.5, 111.5, 111.3, 48.8, 48.6, 47.6, 47.5, 45.8, 45.7, 44.1, 39.6, 34.5, 26.8, 25.4, 8.6, 4.2. MS (ES+) m/z 480.1 (M+1).

Example 4 Synthesis of 6-(4-benzylpiperazin-1-yl)pyridazine-3-carboxylic acid (3-methylbutyl)amide

A stirred mixture of 6-chloropyridazine-3-carboxylic acid (3-methylbutyl)amide (0.113 g, 0.5 mmol), 1-benzylpiperazine (90 mg, 0.5 mmol), tetrabutylammonium bromide (27 mg, 0.084 mmol) and 1,8-diazabicylco[5.4.0]undec-7-ene (152 mg, 1.0 mmol) was heated under reflux in dioxane (10 mL) overnight. The solvent was evaporated. Residue was treated with 2% methanol in water (25 mL). The solid, which precipitated, was filtered off and dried in vacuo to give 138 mg (0.376 mmol) of the title compound in 75% yield. ¹H NMR (300 MHz, CDCl₃) δ 7.98, 7.87, 7.36-7.32, 6.94, 3.76-3.74, 3.57, 3.50-3.46, 2.60-2.58, 1.74-1.68, 1.52-1.48, 0.94. MS (ES+) m/z 368.2 (M+1).

Example 5 Synthesis of 1-(2-phenylcyclopropyl)-3-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}urea

To a solution of [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethyl-phenyl)methanone (123 mg, 0.35 mmol) in DMF (20.0 mL) was added (2-isocyanatocyclopropyl)benzene (111 mg, 0.7 mmol). The mixture was stirred at 60° C. overnight.

After cooling, the mixture was poured into water (120 mL). The white solid, which precipitated, was filtered off and dried in vacuum to give the title product (162 mg) as a white solid in 90% yield.

¹H NMR (300 MHz, CDCl₃) δ 8.01-7.97, 7.73, 7.60, 7.55, 7.32, 7.22-7.10, 7.06, 4.00-3.95, 3.87-3.86, 3.62-3.52, 3.43-3.41, 3.25-3.22, 2.85-2.82, 2.14-2.10, 0.91-0.86. MS (ES+) m/z 511.2 (M+1).

Example 5.1 3-(3-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]-pyridazin-3-yl}-ureido)propionic acid ethyl ester

Following the procedure of Example 5, making variations only as required to use 3-isocyanatopropionic acid ethyl ester in place of (2-isocyanatocyclopropyl)benzene to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (37% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.12, 7.92, 7.74, 7.62, 7.55, 7.36, 7.11, 6.65, 3.95-3.90, 3.59, 3.49-3.40, 3.28, 2.36-2.33, 1.63-1.61, 0.94-0.93.

Example 5.2 1-pentyl-3-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}urea

Following the procedure of Example 5, making variations only as required to use pentylisocyanate in place of (2-isocyanatocyclopropyl)benzene to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a white solid (45.5% yield). ¹H NMR (400 MHz, CDCl₃) δ 10.60, 7.82, 7.74, 7.13, 7.63, 7.56, 7.52, 7.36, 7.08, 4.29, 4.0-4.09, 3.85-3.95, 3.50-3.70, 3.40-3.47, 3.25-3.36, 1.50-1.60, 1.22-1.36, 0.80-0.92. MS (ES+) m/z 465 (M+1).

Example 5.3 1-benzyl-3-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}urea

Following the procedure of Example 5, making variations only as required to use benzylisocyanate in place of (2-isocyanatocyclopropyl)benzene to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a white solid (45.6% yield). ¹H NMR (500 MHz, CDCl₃) δ 12.0, 8.28, 7.80, 7.67, 7.62, 7.32, 7.23, 7.02-7.14, 4.54, 3.85-3.91, 3.69-3.76, 3.28-3.40, 2.94-3.10.

Example 5.4 1-(4-fluorophenyl)-3-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]-pyridazin-3-yl}urea

Following the procedure of Example 5, making variations only as required to use 4-fluorophenylisocyanate in place of (2-isocyanatocyclopropyl)benzene to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)-methanone, the title compound was obtained as a white solid (32.3% yield). ¹H NMR (500 MHz, CDCl₃) δ 12.0, 8.20, 7.53, 7.64, 7.59, 7.39, 7.33, 7.16, 6.91-6.98, 3.96-4.04, 3.83-3.90, 3.52-3.65, 3.37-3.45, 3.20-3.26. MS (ES+) m/z 489 (M+1).

Example 5.5 1-(2-fluorophenyl)-3-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]-pyridazin-3-yl}urea

Following the procedure of Example 5, making variations only as required to use 2-fluorophenylisocyanate in place of (2-isocyanatocyclopropyl)benzene to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)-methanone, the title compound was obtained as a white solid (32% yield). ¹H NMR (500 MHz, CDCl₃) δ 7.90-8.30, 7.99, 7.75, 7.63, 7.57, 7.34, 7.10-7.17, 7.01-7.07, 3.94-4.01, 3.85-3.92, 3.56-3.66, 3.41-3.49, 3.24-3.29.

Example 5.6 1-phenethyl-3-{6-[4-(2-trifluoromethylbenzoyl)-piperazin-1-yl]-pyridazin-3-yl}urea

Following the procedure of Example 5, making variations only as required to use 2-phenylethylisocyanate in place of (2-isocyanatocyclopropyl)benzene to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)-methanone, the title compound was obtained as a white solid (19% yield). ¹H NMR (500 MHz, CDCl₃) δ 7.92, 7.60, 7.64, 7.58, 7.37, 7.13-7.24, 7.09, 3.96-4.03, 3.82-3.89, 3.40-3.56, 3.22-3.34, 2.86.

Example 5.7 1-(4-fluorobenzyl)-3-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]-pyridazin-3-yl}urea

Following the procedure of Example 5, making variations only as required to use 4-fluorobenzylisocyanate in place of (2-isocyanatocyclopropyl)benzene to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)-methanone, the title compound was obtained as a white solid (56% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.13, 7.78, 7.66, 7.60, 7.33, 7.21, 7.09, 6.83, 4.50, 3.91-4.00, 3.73-3.80, 3.34-3.48, 3.05-3.22. MS (ES+) m/z 503 (M+1).

Example 5.8 1-butyl-3-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}urea

Following the procedure of Example 5, making variations only as required to use butylisocyanate in place of (2-isocyanatocyclopropyl)benzene to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a white solid (92% yield). ¹H NMR (500 MHz, CDCl₃) δ 7.84, 7.74, 7.63, 7.56, 7.36, 7.08, 4.00-4.07, 3.88-3.94, 3.54-3.66, 3.42-3.46, 3.27-3.36, 1.51-1.57, 1.30-1.40, 0.89. MS (ES+) m/z 451 (M+1).

Example 5.9 1-cyclopentyl-3-{6-[4-(2-trifluoromethylbenzoyl)-piperazin-1-yl]pyridazin-3-yl}urea

Following the procedure of Example 5, making variations only as required to use cyclopentylisocyanate in place of (2-isocyanatocyclopropyl)benzene to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)-methanone, the title compound was obtained as a white solid (91% yield). ¹H NMR (500 MHz, DMSO-d₆) δ 9.02, 7.82, 7.75, 7.65, 7.58, 7.51, 7.34, 3.91-3.98, 3.67-3.80, 3.46-3.58, 3.36-3.44, 3.11-3.35, 1.80-1.88, 1.46-1.67, 1.30-1.40. MS (ES+) m/z 451 (M+1).

Example 5.10 1-hexyl-3-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}urea

Following the procedure of Example 5, making variations only as required to use hexylisocyanate in place of (2-isocyanatocyclopropyl)benzene to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (50% yield). ¹H NMR (300 MHz, CD₃OD) δ 7.83, 7.76, 7.69, 7.52, 7.44, 7.39, 3.87-4.00, 3.66, 3.50, 3.25-3.43, 1.53-1.67, 1.28-1.48, 0.84-0.98. MS (ES+) m/z 479 (M+1).

Example 5.11 1-heptyl-3-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}urea

Following the procedure of Example 5, making variations only as required to use heptylisocyanate in place of (2-isocyanatocyclopropyl)benzene to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl] (2-trifluoromethylphenyl)methanone, the title compound was obtained as white powder (46% yield). ¹H NMR (300 MHz, DMSO-d₆) δ 9.12, 7.82, 7.75, 7.65, 7.50-7.57, 7.35, 3.69-3.80, 3.45-3.60, 3.38-3.43, 3.28-3.34, 3.20-3.26, 3.06-3.17, 1.45, 1.15-1.28, 0.85.

Example 5.12 1-(3,4-dichlorobenzyl)-3-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]-pyridazin-3-yl}urea

Following the procedure of Example 5, making variations only as required to use 3,4-dichlorobenzylisocyanate in place of (2-isocyanato-cyclopropyl)benzene to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)-methanone, the title compound was obtained as white powder (44% yield). ¹H NMR (300 MHz, DMSO-d₆) δ 9.38, 8.30, 7.85, 7.77, 7.67, 7.59, 7.52-7.57, 7.39, 7.29, 4.38, 3.70-3.82, 3.50-3.62, 3.42-3.47, 3.34-3.38, 3.23-3.29, 3.15-3.20. MS (ES+) m/z 553 (M+1).

Example 5.13 1-cyxlohexyl-3-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]-pyridazin-3-yl}urea

Following the procedure of Example 5, making variations only as required to use cyclohexylisocyanate in place of (2-isocyanatocyclopropyl)benzene to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)-methanone, the title compound was obtained as white powder (34% yield). ¹H NMR (300 MHz, DMSO-d₆) δ 9.05, 7.82, 7.74, 7.65, 7.55, 7.52, 7.35, 3.69-3.79, 3.44-3.58, 3.35-3.42, 3.20-3.26, 3.11-3.18, 1.75-1.84, 1.58-1.67, 1.47-1.55, 1.10-1.35.

Example 6 Synthesis of 2-phenoxy-N-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}acetamide

To a stirred solution of [4-(6-aminopyridazin-3-yl)-piperazin-1-yl]-(2-trifluoromethyl-phenyl)methanone (105 mg, 0.300 mmol) in dichloromethane (10 mL) was added phenoxyacetyl chloride (56 mg, 0.32 mmol) followed by the addition of triethylamine (0.15 mL) at 0° C. The mixture was stirred at ambient temperature overnight. Water was added and the mixture was extracted with ethyl acetate (2×15 mL). The combined organic layer was washed sequentially with diluted HCl, sodium bicarbonate and brine solution, then dried with Na₂SO₄, concentrated. The residue was re-dissolved in small amount of dichloromethane and purified by column chromatography. The title compound was isolated as a white solid in 34% yield (50 mg). ¹H NMR (300 MHz, CDCl₃) δ 9.28, 8.38, 7.75, 7.64, 7.56, 7.35, 7.04, 4.65, 4.01, 3.68, 3.34.

Example 6.1 2- phenylcyclopropanecarboxylic acid (2-phenylcyclopropanecarbonyl) {6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}amide and 2-phenylcyclopropanecarboxylic acid {6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}amide

Following the procedure of Example 6, making variations only as required to use 2-phenylcyclopropanecarbonyl chloride in place of phenoxyacetyl chloride to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)-methanone, both compounds were obtained from the reaction. 2-Phenylcyclopropanecarboxylic acid (2-phenylcyclopropanecarbonyl) {6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}amide was isolated by column chromatography eluting with EtOAc:hexane=40:60 and obtained as a white powder (20% yield). ¹H NMR (300 MHz, CDCl₃) δ 7.73, 7.62, 7.54, 7.34, 7.22, 7.16, 7.04, 6.84, 3.99, 3.82, 3.63, 3.28, 2.62, 2.31, 1.76, 1.38. MS (ES+) m/z 640.3 (M+1). 2-Phenylcyclopropanecarboxylic acid {6-[4-(2-trifluoromethyl-benzoyl)piperazin-1-yl]pyridazin-3-yl}amide was isolated by column chromatography eluting with EtOAc:hexane=50:50 and obtained as a white powder (16% yield). ¹H NMR (300 MHz, CDCl₃) δ 10.36, 8.39, 7.76, 7.64, 7.57, 7.34, 7.18, 7.12, 3.92, 3.52, 3.37, 3.18, 2.64, 2.30, 1.34. MS (ES+) m/z 496.3 (M+1).

Example 6.2 Hexanoic acid {6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}amide

Following the procedure of Example 6, making variations only as required to use hexyanoyl chloride in place of phenoxyacetyl chloride to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a white solid (30% yield). ¹H NMR (300 MHz, CDCl₃) δ 11.65, 8.62, 7.75, 7.65, 7.58, 7.46-7.53, 7.37, 4.08, 3.88, 3.52-3.78, 3.30-3.40, 2.63, 1.72-1.79, 1.24-1.40, 0.90. MS (ES+) m/z 449.7 (M+1).

Example 6.3 4-fluoro-N-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]-pyridazin-3-yl}benzamide

Following the procedure of Example 6, making variations only as required to use 4-fluorobenzoyl chloride in place of phenoxyacetyl chloride to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a light yellow solid (62% yield). ¹H NMR (400 MHz, DMSO-d₆) δ 7.78-7.85, 7.77, 7.66, 7.52, 7.44, 7.25-7.35, 3.10-3.80.

Example 7 Synthesis of {6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}carbamic acid butyl ester

To a stirred solution of [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethyl-phenyl)methanone (100 mg, 0.285 mmol) in dichloromethane (5 mL) was added n-butyl chloroformate (0.285 mmol) in the presence of triethylamine (0.313 mmol) at 0° C. The resulting mixture was stirred at ambient temperature for 24 h and then quenched with water (10 mL). The organic phase was washed with water, saturated NaCl, dried over MgSO₄ and then concentrated in vacuo to afford the desired product as a white solid (0.095 g, 74% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.10, 7.73, 7.63, 7.55, 7.36, 7.04, 4.19, 3.96-4.02, 3.89-3.95, 3.61-3.66, 3.52-3.56, 3.32, 1.64-1.70, 1.38-1.46, 0.95.

Example 7.1 {6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}carbamic acid propyl ester

Following the procedure of Example 7, making variations only as required to use propyl chloroformate in place of n-butyl chloroformate to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a white solid (72% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.10, 7.73, 7.62, 7.55, 7.37, 7.04, 4.14, 3.96-4.02, 3.88-3.94, 3.61-3.66, 3.52-3.56, 3.32, 1.66-1.75, 0.98. MS (ES+) m/z 438 (M+1).

Example 7.2 {6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}carbamic acid isobutyl ester

Following the procedure of Example 7, making variations only as required to use 2-methylpropyl chloroformate in place of n-butyl chloroformate to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a white solid (47% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.09, 7.73, 7.65, 7.63, 7.55, 7.36, 7.04, 3.96, 3.95-4.02, 3.88-3.94, 3.61-3.65, 3.52-3.56, 3.32, 1.94-2.04, 0.96. MS (ES+) m/z 452 (M+1).

Example 7.3 {6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}carbamic acid ethyl ester

Following the procedure of Example 7, making variations only as required to use ethyl chloroformate in place of n-butyl chloroformate to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a light yellow solid (35% yield). ¹H NMR (300 MHz, DMSO-d₆) δ 10.30, 7.82-7.85, 7.76, 7.67, 7.52, 7.37, 4.15, 3.15-3.85, 1.10. MS (ES+) m/z 424 (M+1).

Example 8 Synthesis of 1-(3-cyclopropylpropyl)-3-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}urea

[4-(6-Aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone (200 mg, 0.57 mmol) was slowly added to an ice cold solution of 1,1′-carbonyldiimidazole (110 mg, 0.683 mmol) in anhydrous dichloromethane (15 mL). The temperature was then raised to ambient temperature and the reaction mixture was stirred for another 4 hours. 3-Cyclopropylpropylamine (48.5 mg, 0.569 mmol) was then added to the reaction mixture which was stirred at ambient temperature overnight under nitrogen. The reaction mixture was washed by saturated sodium bicarbonate and brine solution, concentrated and purified by flash column chromatography to yield the product as a white solid (23 mg, 8.5% yield). ¹H NMR (300 MHz, CDCl₃) δ 10.2, 7.68-7.83, 7.72, 7.65, 7.63, 7.55, 7.36, 7.04, 3.95-4.02, 3.83-3.95, 3.50-3.68, 3.40-3.50, 3.26-3.38, 1.60-1.72, 1.17-1.30, 0.71-0.80, 0.44-0.50, −0.06-0.013. MS (ES+) m/z 477 (M+1).

Example 8.1 1-{6-[4-(2,6-difluorobenzoyl)piperazin-1-yl]pyridazin-3-yl}-3-(3-methylbutyl)urea

Following the procedure of Example 8, making variations only as required to use 3-methylbutylamine in place of 3-cyclopropylpropylamine to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2,5-difluorophenyl)methanone, the title compound was obtained as a white solid (27% yield). ¹H NMR (300 MHz, CDCl₃) δ 9.75, 7.68, 7.32-7.43, 7.07, 6.89-7.00, 3.85-4.00, 3.25-3.75, 1.40-1.65, 0.89. MS (ES+) m/z 432.8 (M+1).

Example 8.2 1-cyclopropylmethyl-3-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}urea

Following the procedure of Example 8, making variations only as required to use cyclopropylmethylamine in place of 3-cyclopropylpropylamine to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a white solid (50% yield). ¹H NMR (400 MHz, CDCl₃) δ 7.80-7.54, 7.37, 7.09, 4.07-3.18, 1.12-0.98, 0.52-0.46, 0.27-0.22. MS (ES+) m/z 449.9 (M+1).

Example 8.3 1-(3,3-dimethylbutyl)-3-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}urea

Following the procedure of Example 8, making variations only as required to use 3,3-dimethylbutylamine in place of 3-cyclopropylpropylamine to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a white solid (56% yield). ¹H NMR (400 MHz, CDCl₃) δ 8.04-7.54, 7.37, 7.09, 4.08-3.16, 1.52-1.44, 0.88. MS (ES+) m/z 479.3 (M+1).

Example 8.4 1-(2-cyclopropylethyl)-3-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}urea

Following the procedure of Example 8, making variations only as required to use 2-cyclopropylethylamine in place of 3-cyclopropylpropylamine to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a yellow solid (65% yield). m.p. >300° C. ¹H NMR (300 MHz, CDCl₃) δ7.73, 7.62, 7.55, 7.36, 7.07, 4.04-7.00, 3.94-3.89, 3.64-3.56, 3.47-3.45, 3.40-3.32, 1.46, 0.69-0.66, 0.47-0.38, 0.06-0.00. MS (ES+) m/z 463 (M+1).

Example 8.5 1-(2-isopropoxyethyl)-3-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}urea

Following the procedure of Example 8, making variations only as required to use 2-isopropoxyethylamine in place of 3-cyclopropylpropylamine to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a yellow solid (15% yield). m.p. >300° C. ¹H NMR (300 MHz, CDCl₃) δ7.69, 7.60-7.56, 7.51, 7.35, 3.98-3.92, 3.74-3.64, 3.45-3.44, 3.38-3.19, 3.09-2.97, 2.95-2.86, 2.84-2.77, 2.00-1.74, 1.77-1.74, 1.38. MS (ES+) m/z 470 (M+1).

Example 8.6 1-(3-hydroxy-4,4-dimethylpentyl)-3-{6-[4-(2-trifluoromethylbenzoyl)-piperazin-1-yl]pyridazin-3-yl}urea

Following the procedure of Example 8, making variations only as required to use 3-hydroxy-4,4-dimethylpentylamine in place of 3-cyclopropylpropylamine to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)-methanone, the title compound was obtained as a yellow solid (32% yield). m.p. 218-221° C. MS (ES+) m/z 470 (M+1).

Example 8.7 1-(2-cyclopropylethyl)-3-{6-[4-(2-fluoro-6-trifluoromethylbenzoyl)-piperazin-1-yl]pyridazin-3-yl}urea

Following the procedure of Example 8, making variations only as required to use 2-cyclopropylethylamine in place of 3-cyclopropylpropylamine to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-fluoro-6-trifluoromethylphenyl)-methanone, the title compound was obtained as a white powder (48% yield). ¹H NMR (400 MHz, CDCl₃) δ 8.14, 7.58-7.54, 7.43, 7.38-7.34, 7.10-7.05, 4.01-3.94, 3.58-3.32, 1.46, 0.72-0.67, 0.45-0.39, 0.08-0.02.

Example 8.8 1-(2-cyclopropylethyl)-3-{6-[4-(5-fluoro-2-trifluoromethylbenzoyl)-piperazin-1-yl]pyridazin-3-yl}urea

Following the procedure of Example 8, making variations only as required to use 2-cyclopropylethylamine in place of 3-cyclopropylpropylamine to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](5-fluoro-2-trifluoromethylphenyl)-methanone, the title compound was obtained as a white powder (30% yield). ¹H NMR (400 MHz, CDCl₃) δ 8.30, 7.76-7.71, 7.23, 7.10-7.06, 4.00-3.97, 3.91-3.87, 3.65-3.45, 3.88-3.40, 1.26-1.24, 0.74-0.68, 0.44-0.43, 0.05-0.04.

Example 8.9 1-(2-cyclopropylethyl)-3-{6-[4-(2,6-difluorobenzoyl)piperazin-1-yl]-pyridazin-3-yl}urea

Following the procedure of Example 8, making variations only as required to use 2-cyclopropylethylamine in place of 3-cyclopropylpropylamine to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2,6-difluorophenyl)methanone, the title compound was obtained as a white powder (14.1% yield). ¹H NMR (400 MHz, CDCl₃) δ 9.16, 7.89, 7.62-7.52, 7.37, 7.26-7.21, 3.81-3.78, 3.58-3.52, 3.44-3.37, 3.32-3.28, 3.24-3.18, 1.36, 0.70-0.65, 0.42-0.37, 0.07-0.03.

Example 8.10 1-(3-cyclopropylpropyl)-3-{6-[4-(5-fluoro-2-trifluoromethylbenzoyl)-piperazin-1-yl]pyridazin-3-yl}urea

Following the procedure of Example 8, making variations only as required to use [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone in place of [4-(6-aminopyridazin-3-yl)piperazin-1-yl](5-fluoro-2-trifluoromethylphenyl)methanone to react with 3-cyclopropylpropylamine, the title compound was obtained as a white powder (15% yield). ¹H NMR (400 MHz, CDCl₃) □ 8.32-8.31, 7.76-7.73, 7.76-7.73, 7.25-7.22, 7.13-7.06, 4.14-3.98, 3.95-3.85, 3.68-3.52, 3.40-3.32, 1.70-1.60, 1.28-1.21, 0.65-0.62, 0.40-0.36, 0.03-0.02.

Example 8.11 1-(4-methylpentyl)-3-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}urea

Following the procedure of Example 8, making variations only as required to use 4-methylpentylamine in place of 3-cyclopropylpropylamine to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a white solid (0.039 g, 29% yield). ¹H NMR (300 MHz, CDCl₃) δ 10.7-10.2, 7.85-7.77, 7.73, 7.65-7.5, 7.35, 7.1-7.07, 4.08-3.95, 3.94-3.83, 3.64-3.52, 3.48-3.38, 3.35-3.21, 1.6-1.45, 1.25-1.12, 0.83. ¹³C NMR (75 MHz, CDCl₃) δ 167.5, 156.8, 155.8, 151.7, 134.4, 132.3, 129.4, 127.2, 126.8, 126.7, 125.4, 121.8, 121.3, 118.4, 46.4, 46.02, 45.8, 40.3, 36.1, 28.3, 27.8, 22.5. MS (ES+) m/z 479.4 (M+1).

Example 9 Synthesis of 6-[4-(2,5-dichlorobenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide

A mixture of 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-methylbutyl)amide (0.255 mmol), 2,5-dichlorobenzoic acid (0.31 mmol), 1,8-diazabicylco[5.4.0]undec-7-ene (0.51 mmol) and 1-hydroxybenozotriazole hydrate (0.31 mmol) in DMF (2 mL) was stirred at ambient temperature for 15 min. 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide (0.31 mmol) was then added. The mixture was stirred at ambient temperature overnight, and then diluted with EtOAc (50 mL) and washed with aqueous saturated NaHCO₃ (2×20 mL) and brine (2×20 mL). The organic extract was dried over anhydrous Na SO₄, concentrated, and purified by flash chromatography to give the title compound as a white solid (102 mg, 89% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.07, 7.85, 7.32-7.40, 7.01, 4.01-4.08, 3.77-3.93, 3.35-3.55, 1.65-1.75, 1.52, 0.94. MS (ES+) m/z 450 (M+1).

Example 9.1 6-[4-(5-methyl-2-trifluoromethylfuran-3-carbonyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 9, making variations only as required to use 5-methyl-2-trifluoromethylfuran-3-carboxylic acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (53% yield). m.p. 128-130° C. ¹H NMR (500 MHz, CDCl₃) δ 8.08, 7.99, 7.01, 6.15, 3.89-3.94), 3.77-3.82, 3.52-3.60, 2.39, 1.52, 0.71-0.80, 0.45-0.49, 0.08-0.13. MS (ES+) m/z 452 (M+1).

Example 9.2 6-[4-(2-chloropyridine-3-carbonyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 9, making variations only as required to use 2-chloropyridine-3-carboxylic acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-ylpyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (44% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.50, 8.08, 7.99, 7.71, 7.37, 7.02, 4.05-4.13, 3.78-3.95, 3.34-3.60, 1.51, 0.71-0.80, 0.45-0.49, 0.08-0.12. MS (ES+) m/z 415 (M+1).

Example 9.3 6-[4-(2-methyl-5-trifluoromethyloxazole-4-carbonyl)piperazin-1-yl]-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 9, making variations only as required to use 2-methyl-5-trifluoromethyloxazole-4-carboxylic acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (58% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.05, 7.98, 6.99, 3.75-3.95, 3.50-3.59, 2.55, 1.51, 0.71-0.80, 0.45-0.49, 0.06-0.12. MS (ES+) m/z 453 (M+1).

Example 9.4 6-[4-(2,6-dichloropyridine-3-carbonyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 9, making variations only as required to use 2,6-dichloropyridine-3-carboxylic acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (19% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.06, 7.97, 7.65, 7.37, 7.01, 3.70-4.10, 3.29-3.61, 1.52, 0.68-0.80, 0.42-0.49, 0.06-0.13. MS (ES+) m/z 449 (M+1).

Example 9.5 6-[4-(1-benzyl-5-trifluoromethyl-1h-[1,2,3]triazole-4-carbonyl)-piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide

Following the procedure of Example 9, making variations only as required to use 1-benzyl-5-trifluoromethyl-1H-[1,2,3]triazole-4-carboxylic acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-methylbutyl)amide, the title compound was obtained as a white powder (32% yield). ¹H NMR (300 MHz, DMSO-d₆) δ 8.03, 7.81, 7.33-7.27, 6.86, 5.92, 5.39, 3.71, 3.47, 3.05, 2.63, 2.43, 1.65, 1.48, 0.92. MS (ES+) m/z 531.2 (M+1).

Example 9.6 6-[4-(3-benzyl-5-trifluoromethyl-3h-[1,2,3]triazole-4-carbonyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide

Following the procedure of Example 9, making variations only as required to use 3-benzyl-5-trifluoromethyl-3H-[1,2,3]triazole-4-carboxylic acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-methylbutyl)amide, the title compound was obtained as a white powder (37% yield). ¹H NMR (300 MHz, DMSO-d₆) δ 8.04, 7.83, 7.36, 7.28, 6.99, 5.69, 3.94, 3.84, 3.70, 3.46, 1.75-1.61, 1.49, 0.91. MS (ES+) m/z 531.2 (M+1).

Example 9.7 6-[4-(2-methyl-5-trifluoromethyl-2H-[1,2,3]triazole-4-carbonyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide

Following the procedure of Example 9, making variations only as required to use 2-methyl-5-trifluoromethyl-2H-[1,2,3]triazole-4-carboxylic acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-methylbutyl)amide, the title compound was obtained as a white powder (15% yield). ¹H NMR (300 MHz, DMSO-d₆) δ 8.05, 7.83, 7.00, 4.28, 3.97-3.67, 3.51-3.45, 1.75-1.68, 1.49, 0.92. MS (ES+) m/z 455.2 (M+1).

Example 9.8 6-[4-(5-trifluoromethyl-3h-imidazole-4-carbonyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide

Following the procedure of Example 9, making variations only as required to use 5-trifluoromethyl-3H-imidazole-4-carboxylic acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-ylpyridazine-3-carboxylic acid (3-methylbutyl)amide, the title compound was obtained as a white powder (48% yield). ¹H NMR (300 MHz, DMSO-d₆) δ 8.03, 7.86, 7.70, 6.99, 3.80, 3.46, 1.75-1.62, 1.48, 0.92. MS (ES+) m/z 440.2 (M+1).

Example 9.9 6-[4-(2-methanesulfonylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide

Following the procedure of Example 9, making variations only as required to use 2-methanesulfonylbenzoic acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-methylbutyl)amide, the title compound was obtained as a white solid (97% yield). ¹H NMR (400 MHz, CDCl₃) δ 8.11, 8.03, 7.85, 7.74-7.62, 7.38, 4.32-3.33, 3.27, 1.73-1.62, 1.52-1.46, 0.94. MS (ES+) m/z 484.3 (M+1).

Example 9.10 6-[4-(2,2-dimethylbutyryl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 9, making variations only as required to use 2,2-dimethylbutyric acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-ylpyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (46% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.05, 8.01, 6.98, 3.86-3.73, 3.57, 1.68, 1.52, 0.92, 0.80-0.72, 0.49-0.45, 0.14-0.08. MS (ES+) m/z 374.3 (M+1).

Example 9.11 6-[4-(2,2-dimethylpentanoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 9, making variations only as required to use 2,2-dimethylpentanoic acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (61% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.05, 7.96, 6.98, 3.85-3.72, 3.56, 1.64-1.45, 1.23, 0.96, 0.82-0.62, 0.49-0.45, 0.12-0.07. MS (ES+) m/z 388.2 (M+1).

Example 9.12 6-[4-(5-fluoro-2-methoxybenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 9, making variations only as required to use 5-fluoro-2-methoxybenzoic acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)-amide, the title compound was obtained as a white solid (61% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.03, 7.96, 7.10-6.98, 6.86-6.84, 4.03-3.37, 1.51, 0.80-0.72, 0.49-0.44, 0.15-0.10. MS (ES+) m/z 428.1 (M+1).

Example 9.13 6-[4-(2-dimethylaminobenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 9, making variations only as required to use 2-dimethylaminobenzoic acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (61% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.04, 7.96, 7.36-7.25, 7.05-6.94, 4.17-3.40, 2.80, 1.51, 0.80-0.73, 0.47-0.42, 0.12-0.07.

Example 9.14 6-[4-(2-chloro-5-dimethylaminobenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 9, making variations only as required to use 2-chloro-5-dimethylaminobenzoic acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)-amide, the title compound was obtained as a white solid (53% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.04, 7.96, 7.39, 6.94, 6.66, 6.55, 4.14-3.32, 2.93, 1.52, 0.75-0.69, 0.48-0.42, 0.11-0.05. MS (ES+) m/z 457.4 (M+1).

Example 9.15 6-[4-(2,5-dimethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 9, making variations only as required to use 2,5-dimethylbenzoic acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (56% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.05, 7.96, 7.16-7.11, 7.03-6.97, 4.12-3.67, 2.23, 2.22, 1.52, 0.82-0.69, 0.48-0.42, 0.11-0.05. MS (ES+) m/z 408.3 (M+1).

Example 9.16 6-[4-(2,5-dichlorobenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 9, making variations only as required to use 2,5-dichlorobenzoic acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (56% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.05, 7.96, 7.38-7.30, 6.97, 4.12-3.23, 1.50, 0.80-0.67, 0.51-0.38, 0.16-0.06. MS (ES+) m/z 448.2 (M+1).

Example 9.17 6-[4-(1-methyl-1H-pyrrole-2-carbonyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 9, making variations only as required to use 1-methyl-1H-pyrrole-2-carboxylic acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)-amide, the title compound was obtained as a white powder (51.8% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.07, 8.01, 7.00, 6.75, 6.40, 6.12, 4.00-3.80, 3.58, 1.52, 0.76, 0.48, 0.10. MS (ES+) m/z 383 (M+1).

Example 9.18 6-[4-(4,4,4-trifluorobut-2-enoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 9, making variations only as required to use 4,4,4-trifluorobut-2-enoic acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white powder (19.6% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.09, 8.00, 7.00, 6.81, 3.96-3.88, 3.78, 3.57, 1.53, 0.76, 0.48, 0.10. MS (ES+) m/z 398 (M+1).

Example 9.19 6-[4-(1-hydroxycyclopropanecarbonyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 9, making variations only as required to use 1-hydroxycyclopropanecarboxylic acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white powder (53.4% yield). ¹H NMR (500 MHz, CDCl₃) δ8.07, 8.03, 7.01, 3.98-3.73, 3.58, 1.53, 1.16, 1.02, 0.76, 0.48, 0.10. MS (ES+) m/z 360 (M+1).

Example 9.20 6-[4-(4,4,4-trifluoro-3-hydroxy-3-trifluoromethylbutyryl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 9, making variations only as required to use 4,4,4-trifluoro-3-hydroxy-3-trifluoromethylbutyryic acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white powder (45.6% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.08, 8.03, 7.98, 7.00, 3.95-3.71, 3.56, 2.89, 1.55, 0.75, 0.48, 0.10. ¹³C NMR (CDCl₃) δ 168.5, 162.8, 159.8, 145.8, 127.3, 112.5, 45.5, 44.5, 44.1, 41.3, 39.7, 34.5, 27.2, 8.6, 4.2. MS (ES+) m/z 484 (M+1).

Example 9.21 6-[4-(4,4,4-trifluoro-3-hydroxy-3-methylbutyryl)piperazin-1-yl]-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 9, making variations only as required to use 4,4,4-trifluoro-3-hydroxy-3-methylbutyric acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white powder (50.1% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.07, 7.96, 6.98, 6.23, 4.05-3.52, 2.90, 2.47, 1.53-1.43, 0.76, 0.46, 0.09. MS (ES+) m/z 430 (M+1).

Example 9.22 6-(4-cyclobutanecarbonylpiperazin-1-yl)pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 9, making variations only as required to use 4-cyclobutanecarboxylic acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white powder (45.6% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.03, 7.97, 6.97, 3.82-3.64, 3.57-3.49, 3.26, 2.43-2.27, 2.22-2.05 2.02-1.81, 1.50, 0.75, 0.46, 0.08. MS (ES+) m/z 358 (M+1).

Example 9.23 6-[4-(2-trifluoromethylcyclopropanecarbonyl)piperazin-1-yl]-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 9, making variations only as required to use 2-trifluoromethylcyclopropanecarboxylic acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white powder (30.9% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.03, 7.98, 7.00, 3.97-3.57, 2.20, 1.65, 1.50, 1.26, 0.75, 0.46, 0.09. MS (ES+) m/z 412 (M+1).

Example 9.24 6-[4-(4,4,4-trifluoro-3-trifluoromethylbut-2-enoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 9, making variations only as required to use 4,4,4-trifluoro-3-trifluoromethylbut-2-enoic acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white powder (45.4% yield). ¹H NMR (CDCl₃) δ 8.07, 7.97, 7.10, 7.01, 3.87-3.74, 3.58-3.50, 1.54-1.47, 0.78-0.68, 0.48-0.42, 0.10-0.05. ¹³C NMR (CDCl₃) δ 162.8, 161.1, 159.8, 145.8, 135.2, 135.1, 127.3, 124.5, 112.7, 45.5, 44.4, 44.3, 40.9, 39.7, 34.5, 8.6, 4.2. MS (ES+) m/z 466 (M+1).

Example 9.25 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid cyclobutylmethylamide

Following the procedure of Example 9, making variations only as required to use 2-trifluoromethylbenzoic acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid cyclobutylmethylamide, the title compound was obtained as a white powder (45.0% yield). ¹H NMR (CDCl₃) δ 8.04, 7.83, 7.72, 7.64-7.51, 7.32, 7.00, 4.10-4.01, 3.90-3.66, 3.49-3.27, 2.63-2.47, 2.11-1.67. ¹³C NMR (CDCl₃) δ167.7, 162.9, 159.8, 145.4, 134.2, 132.4, 129.6, 127.4, 126.9, 126.8, 125.4, 121.8, 112.8, 46.4, 44.6, 41.2, 35.1, 25.7, 18.3. MS (ES+) m/z 448 (M+1).

Example 9.26 6-{4-[2-(2-trifluoromethylphenyl)acetyl]piperazin-1-yl}pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 9, making variations only as required to use (2-trifluoromethylphenyl)acetic acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-ylpyridazine-3-carboxylic acid (2-cyclopropylethyl)-amide, the title compound was obtained as a white solid (78.7% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.03, 7.97, 7.67-7.64, 7.53-7.48, 7.39-7.35, 6.96, 3.91, 3.87-3.67, 3.66-3.6, 3.58-3.51, 1.53-1.46, 0.78-0.64, 0.48-0.42, 0.10-0.06. ¹³C NMR (75 MHz, CDCl₃) δ 168.8, 162.9, 159.9, 145.3, 133.2, 132.0, 131.5, 128.5, 128.2, 127.2, 127.0, 126.3, 126.2, 125.5, 112.3, 45.0, 44.7, 44.2, 41.2, 39.6, 37.13, 37.11, 34.4, 8.6, 4.2. MS (ES+) m/z 462.2 (M+1).

Example 9.27 6-[4-(2-cyanobenzoyl)piperazin-1-yl]-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 9, making variations only as required to use 2-cyanobenzoic acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (25.8% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.05, 7.97, 7.76-7.72, 7.69-7.66, 7.58-7.55, 7.53-7.43, 6.99, 4.3-3.94, 3.88-3.85, 3.58-3.51, 1.49, 0.78-0.65, 0.48-0.37, 0.16-0.02. ¹³C NMR (75 MHz, CDCl₃) δ166.5, 162.8, 159.9, 145.3, 139.3, 133.3, 133.04, 129.9, 127.6, 127.03, 116.8, 112.4, 109.9, 46.4, 44.7, 44.6, 41.6, 39.6, 34.4, 8.6, 4.1. MS (ES+) m/z 405.2 (M+1).

Example 9.28 6-[4-(4-trifluoromethylpridine-3-carbonyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide

Following the procedure of Example 9, making variations only as required to use 4-trifluoromethylpyridine-3-carboxylic acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-methylbutyl)amide, the title compound was obtained as a white powder (69% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.87, 8.69, 8.05, 7.82, 7.62, 7.00, 4.10-3.69, 3.51-3.44, 3.38-3.35, 1.75-1.61, 1.52-1.45, 0.90. MS (ES+) m/z 451.3 (M+1).

Example 9.29 6-[4-(4,4,4-trifluoro-3-methylbut-2-enoyl)piperazin-1-yl]-pyridazine-3-carboxylic acid (3-methylbutyl)amide

Following the procedure of Example 9, making variations only as required to use to use 4,4,4-trifluoro-3-methylbut-2-enoic acid in place of 2,5-dichlorobenzoic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-methylbutyl)amide, the title compound was obtained as a white powder (62% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.05, 7.83, 7.00, 6.55, 3.86-3.83, 3.80-3.73, 3.62-3.60, 3.48, 2.01, 1.75-1.62, 1.49, 0.92. MS (ES+) m/z 414.4 (M+1).

Example 9.30 6-[4-(1-trifluoromethylcyclopropanecarbonyl)piperazin-1-yl]-pyridazine-3-carboxylic acid (3-methylbutyl)amide

Following the procedure of Example 9, making variations only as required to use 1-trifluoromethylcyclopropanecarboxylic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-methylbutyl)amide, the title compound was obtained as a white powder (72% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.05, 7.83, 6.98, 3.90-3.80, 3.48, 1.66, 1.48, 1.39-1.35, 1.18-1.14, 0.92. MS (ES+) m/z 414.2 (M+1).

Example 9.31 6-[4-(pyridine-2-carbonyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 9, making variations only as required to use pyridine-2-carboxylic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white powder (70% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.60-8.58, 8.03, 7.98, 7.86-7.79, 7.73-7.71, 7.39-7.35, 6.98, 3.96-3.83, 3.54, 1.50, 0.78-0.69, 0.47-0.41, 0.08-0.05. MS (ES+) m/z 381.2 (M+1).

Example 9.32 6-[4-(2-trifluoromethylfuran-3-carbonyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 9, making variations only as required to use 2-trifluoromethylfuran-3-carboxylic acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white powder (71% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.04, 7.96, 7.56, 7.00, 6.54, 3.9-3.7, 3.6-3.5, 1.49, 0.79-0.66, 0.47-0.41, 0.09-0.04. ¹³C NMR (300 MHz, CDCl₃) δ 161.78, 160.01, 145.60, 145.05, 138.14, 137.57, 127.15, 121.74, 120.54, 112.54, 110.88, 46.33, 44.59, 41.43, 39.67, 34.52, 8.64, 4.23. MS (ES+) m/z 438.2 (M+1).

Example 10 Synthesis of 6-[4-(5-trifluoromethyl-3h-[1,2,3]triazole-4-carbonyl)piperazin-1-yl]-pyridazine-3-carboxylic acid (3-methylbutyl)amide

6-[4-(3-Benzyl-5-trifluoromethyl-3H-[1,2,3]triazole-4-carbonyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide (0.4 g, 0.75 mmol) was dissolved in 10 mL of MeOH with 3 drops of acetic acid and 0.2 g of 10% Pd/C was added. The reaction mixture was kept under normal pressure of H₂ at ambient temperature overnight. After filtration the reaction mixture was evaporated under reduced pressure and the residue was recrystallized from 3 mL of EtOH to give 120 mg (36% yield) of 6-[4-(5-trifluoromethyl-3H-[1,2,3]triazole-4-carbonyl)-piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide as a white powder. ¹H NMR (500 MHz, Acetone-d₆) 88.18, 7.91, 7.32, 3.92-3.72, 3.45, 1.67, 1.52, 0.92.

Example 11 Synthesis of 6-[4-(2-trifluoromethylbenzyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide

A mixture of 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-methylbutyl)amide (0.255 mmol), 2-trifluoromethylbenzyl chloride (0.255 mmol), and 1,8-diazabicylco[5.4.0]undec-7-ene (0.77 mmol) was stirred and heated at 60° C. overnight. The reaction mixture was then diluted with EtOAc (100 mL) and washed with aqueous saturated NaHCO₃ (2×20 mL) and brine (2×20 mL).

The organic layer was dried over anhydrous Na₂SO₄, concentrated, and purified by flash chromatography to give the title compound as a white solid (80 mg, 72% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.00, 7.86, 7.82, 7.65, 7.55, 7.37, 6.95, 3.74-3.79, 3.73, 3.46-3.52, 2.62, 1.65-1.76, 1.52, 0.94. MS (ES+) m/z 436 (M+1).

Example 11.1 6-[4-(2-trifluoromethylbenzyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 11, making variations only as required to use 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide in place of 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-methylbutyl)amide to react with 2-trifluoromethylbenzyl chloride, the title compound was obtained as a white solid (32% yield). m.p. 106-108° C. ¹H NMR (500 MHz, CDCl₃) δ 7.97-8.04, 7.83, 7.65, 7.55, 7.37, 6.96, 3.77, 3.73, 3.56, 2.63, 1.52, 0.71-0.80, 0.45-0.49, 0.08-0.13. MS (ES+) m/z 434 (M+1).

Example 11.2 6-[4-(5-fluoro-2-trifluoromethylbenzyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 11, making variations only as required to use 5-fluoro-2-trifluoromethylbenzyl chloride in place of 2-trifluoromethylbenzyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (40% yield). ¹H NMR (300 MHz, CDCl₃) δ 7.95-8.01, 7.57-7.68, 7.04, 6.95, 3.79, 3.71, 3.56, 2.64, 1.51, 0.68-0.82, 0.43-0.51, 0.06-0.13. MS (ES+) m/z 452 (M+1).

Example 11.3 6-[4-(4-fluoro-2-trifluoromethylbenzyl)-piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 11, making variations only as required to use 4-fluoro-2-trifluoromethylbenzyl chloride in place of 2-trifluoromethylbenzyl chloride to react with 6-piperazin-1-ylpyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (38% yield). ¹H NMR (300 MHz, CDCl₃) δ 7.96-8.04, 7.81, 7.36, 7.20-7.29, 6.96, 3.76, 3.68, 3.56, 2.61, 1.51, 0.68-0.84, 0.43-0.51, 0.06-0.13. MS (ES+) m/z 452 (M+1).

Example 11.4 6-[4-(5-chloro-2-trifluoromethylbenzyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 11, making variations only as required to use 5-chloro-2-trifluoromethylbenzyl chloride in place of 2-trifluoromethylbenzyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (48% yield). ¹H NMR (300 MHz, CDCl₃) δ 7.96-8.05, 7.87, 7.58, 7.34, 6.97, 3.80, 3.70, 3.56, 2.64, 1.53, 1.51, 0.70-0.83, 0.43-0.51, 0.07-0.13. MS (ES+) m/z 468 (M+1).

Example 11.5 6-[4-(2-chloro-4-fluorobenzyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 11, making variations only as required to use 2-chloro-4-fluorobenzyl chloride in place of 2-trifluoromethylbenzyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (26% yield). ¹H NMR (300 MHz, CDCl₃) δ 7.92-8.03, 7.38-7.50, 7.06-7.14, 6.88-7.03, 3.68-3.78, 3.62, 3.46-3.58, 2.55-2.69, 1.42-1.54, 0.68-0.80, 0.40-0.49, 0.02-0.13. MS (ES+) m/z 418 (M+1).

Example 11.6 6-[4-(2,5-dichlorobenzyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 11, making variations only as required to use 2,5-dichlorobenzyl chloride in place of 2-trifluoromethylbenzyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (43% yield). ¹H NMR (300 MHz, CDCl₃) δ 7.96-8.04, 7.53, 7.16-7.33, 6.96, 3.75-3.84, 3.64, 3.56, 2.62-2.70, 1.53, 1.51, 0.70-0.83, 0.43-0.51, 0.06-0.13. MS (ES+) m/z 434 (M+1).

Example 11.7 6-[4-(5-fluoro-2-trifluoromethylbenzyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide

Following the procedure of Example 11, making variations only as required to use 5-fluoro-2-trifluoromethylbenzyl chloride in place of 2-trifluoromethylbenzyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-methylbutyl)amide, the title compound was obtained as a white solid (34% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.02, 7.82-7.92, 7.57-7.68, 7.00-7.09, 6.96, 3.79, 3.71, 3.50, 2.64, 1.64-1.78, 1.51, 0.94. MS (ES+) m/z 454 (M+1).

Example 11.8 6-[4-(2,4-dichlorobenzyl)-piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 11, making variations only as required to use 2,4-dichlorobenzyl chloride in place of 2-trifluoromethylbenzyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a light yellow solid (75% yield). ¹H NMR (300 MHz, CDCl₃) δ 7.95-8.02, 7.44, 7.38, 7.23, 6.93, 3.70-3.77, 3.60-3.63, 3.54, 2.60-2.65, 1.50, 0.74, 0.45, 0.08. MS (ES+) m/z 434 (M+1).

Example 11.9 6-[4-(5-fluoro-2-trifluoromethylbenzyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-cyclopropylpropyl)amide

Following the procedure of Example 11, making variations only as required to use 5-fluoro-2-trifluoromethylbenzyl chloride in place of 2-trifluoromethylbenzyl chloride to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-cyclopropylpropyl)amide, the title compound was obtained as a light yellow solid (34% yield). ¹H NMR (300 MHz, CDCl₃) δ 7.98, 7.88, 7.55-7.65, 7.2, 6.93, 3.68-3.85, 3.50, 2.60, 1.70, 1.25, 0.65, 0.40, 0.09. MS (ES+) m/z 466 (M+1).

Example 11.10 Synthesis of 6-[4-(5-fluoro-2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid pent-4-enylamide

Following the procedure of Example 11, making variations only as required to use 5-fluoro-2-(trifluoromethyl)benzyl chloride in place of 2-trifluoromethylbenzyl chloride to react with 6-piperazin-1-ylpyridazine-3-carboxylic acid pent-4-enylamide, the title compound was obtained as a white powder (17.3% yield). ¹H NMR (300 MHz, CDCl₃) δ 7.99, 7.92, 7.77, 7.27, 7.11, 7.00, 5.91-5.78, 5.09-4.95, 4.08-3.65, 3.47-3.27, 2.18-2.11, 1.75-1.65. ¹³C NMR (75 MHz, CDCl₃) δ 166.1, 165.7, 162.9, 162.7, 160.2, 145.5, 138.0, 129.3, 129.6, 129.5, 116.7, 114.9, 114.8, 114.6, 112.4, 46.3, 44.4, 41.2, 38.7, 31.1, 28.9. MS (ES+) m/z 466.3 (M+1).

Example 12 Synthesis of 6-[4-(2-aminobenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide

6-[4-(2-Nitrobenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methyl-butyl)amide (100 mg, 0.235 mmol) was hydrogenated with 10 mg 10% Pd/C as catalyst at ambient temperature under 1 atm for 24 hours. The mixture was filtered through a celite cake. The filtrate was concentrated and purified by flash chromatography (ethyl acetate) to give a white solid (83% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.05, 7.86, 7.19-7.23, 7.10-7.13, 6.99, 4.40, 3.74-3.88, 3.50, 1.65-1.75, 1.52, 0.94. MS (ES+) m/z 397 (M+1).

Example 13 Synthesis of {6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}carbamic acid 3,3-dimethylbutyl ester

To a solution of [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethyl-phenyl)methanone (200 mg, 0.57 mmol) in 10 mL of dioxane was added trichloromethyl chloroformate (112.7 mg, 0.57 mmol) and stirred at ambient temperature. After 30 minutes 3,3-dimethylbutan-1-ol (175.5 mg, 1.71 mmol) and triethylamine (57.6 mg, 0.57 mmol) were added and the temperature was raised to 80° C. The mixture was stirred for 3 h under N₂, and then concentrated. The residue was dissolved in dichloromethane (100 mL), and washed with 1 N HCl (2×20 mL), saturated NaHCO₃ (2×20 mL) and finally with brine (2×20 mL). The combined organic extract was dried over anhydrous Na₂SO₄, concentrated, and then purified by column chromatography eluted with hexane:ethyl acetate (1:2). The product was obtained as a white solid (30 mg, 11% yield). ¹H NMR (300 MHz, DMSO-d₆) δ 10.38, 7.89, 7.83, 7.77, 7.67, 7.54, 7.47, 4.14, 3.10-3.90, 1.55, 0.95.

Example 13.1 {6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}carbamic acid 2-cyclopropylethyl ester

Following the procedure of Example 13, making variations only as required to use 2-cyclopropylethanol in place of 3,3-dimethylbutan-1-ol to react with [4-(6-aminopyridazin-3-yl)piperazin-1-yl](2-trifluoromethylphenyl)methanone, the title compound was obtained as a white solid (8.3% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.11, 7.73, 7.65, 7.63, 7.55, 7.36, 7.04, 4.25, 3.95-4.02, 3.88-3.94, 3.61-3.65, 3.52-3.56, 3.32, 1.58, 0.71-0.80, 0.44-0.50, 0.05-0.013. MS (ES+) m/z 464 (M+1).

Example 14 Synthesis of 6-[4-(4,4,4-trifluoro-2-methylbutyryl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide

A mixture of TFA salt of 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-methylbutyl)amide (100 mg, 0.25 mmol), 4,4,4-trifluoro-2-methylbutyric acid (47.8 mg, 0.31 mmol), 1,8-diazabicylco[5.4.0]undec-7-ene (77.8 mg, 0.51 mmol) and 1-hydroxy-benozotriazole hydrate (41.4 mg, 0.31 mmol) in DMF (2 mL) was stirred at ambient temperature for 15 minutes. 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide (47.6 mg, 0.31 mmol) was added to this solution. The reaction mixture was stirred at ambient temperature overnight and then diluted with ethyl acetate (50 mL) and washed with aqueous saturated NaHCO₃ (2×20 mL) and finally with brine (2×20 mL). The organic extract was dried over anhydrous Na₂SO₄, concentrated, and then purified by column chromatography eluted with hexanesethyl acetate (1:2). The product was obtained as a white flaky solid (80 mg, 75% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.07, 7.85, 7.01, 3.60-4.00, 3.50, 3.15, 2.80, 2.21, 1.70, 1.50, 1.25, 0.95. MS (ES+) m/z 41 (M+1).

Example 14.1 6-[4-(4,4,4-trifluoro-3-methylbutyryl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide

Following the procedure of Example 14, making variations only as required to use 4,4,4-trifluoro-3-methylbutyric acid in place of 4,4,4-trifluoro-2-methylbutyric acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-methylbutyl)amide, the title compound was obtained as a white flaky solid (63% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.07, 7.85, 7.00, 3.69-3.98, 3.67, 3.50, 3.00, 2.71, 2.35, 1.70, 1.50, 1.20, 0.95. MS (ES+) m/z 415 (M+1).

Example 14.2 6-[4-(4,4,4-trifluorobutyryl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide

Following the procedure of Example 14, making variations only as required to use 4,4,4-trifluorobutyric acid in place of 4,4,4-trifluoro-2-methylbutyric acid to react with 6-piperazin-1-yl-pyridazin-3-carboxylic acid (3-methylbutyl)amide, the title compound was obtained as a white flaky solid (49% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.07, 7.85, 7.00, 3.91, 3.82, 3.72, 3.67, 3.50, 2.50-2.67, 1.70, 1.50, 0.95. MS (ES+) m/z 402 (M+1).

Example 14.3 6-[4-(6-chloropyridine-2-carbonyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide

Following the procedure of Example 14, making variations only as required to use 6-chloropyridine-2-carboxylic acid in place of 4,4,4-trifluoro-2-methylbutyric acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-methylbutyl)amide, the title compound was obtained as a white flaky solid (12% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.05, 7.87, 7.82, 7.70, 7.43, 7.00, 3.80-4.00, 3.50, 1.70, 1.53, 0.95. MS (ES+) m/z 417 (M+1).

Example 14.4 6-[4-(2-methylcyclohexanecarbonyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 14, making variations only as required to use 2-methylcyclohexanecarboxylic acid in place of 4,4,4-trifluoro-2-methylbutyric acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (60% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.08, 8.00, 7.00, 3.50-4.00, 2.70, 2.05, 1.20-1.90, 0.90, 0.75, 0.45, 0.10. MS (ES+) m/z 400 (M+1).

Example 14.5 6-[4-(3-methylcyclohexanecarbonyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 14, making variations only as required to use 3-methylcyclohexanecarboxylic acid in place of 4,4,4-trifluoro-2-methylbutyric acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (27% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.06, 7.99, 6.99, 3.89, 3.79, 3.65-3.72, 3.56, 2.55, 1.20-1.86, 0.99, 0.92, 0.75, 0.47, 0.10. MS (ES+) m/z 400 (M+1).

Example 14.6 6-[4-(4-methylcyclohexanecarbonyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 14, making variations only as required to use 4-methylcyclohexanecarboxylic acid in place of 4,4,4-trifluoro-2-methylbutyric acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a white solid (43% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.07, 7.09, 7.05, 3.89, 3.79, 3.64-3.70, 3.56, 2.40-2.60, 1.65-1.88, 1.50-1.62, 0.99, 0.91, 0.75, 0.48, 0.10. MS (ES+) m/z 400 (M+1).

Example 14.7 2-{4-[6-(2-cyclopropylethylcarbamoyl)pyridazin-3-yl]piperazine-1-carbonyl}benzoic acid methyl ester

Following the procedure of Example 14, making variations only as required to use phthalic acid monomethyl ester in place of 4,4,4-trifluoro-2-methylbutyric acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide, the title compound was obtained as a light yellow solid (97% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.02-8.06, 7.96, 7.88, 7.60, 7.48, 7.30, 6.98, 3.72-4.02, 3.54, 3.33, 1.49, 0.74, 0.45, 0.08. MS (ES+) m/z 438 (M+1).

Example 14.8 6-[4-(3,3,3-trifluoro-2-hydroxy-2-methylpropionyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 14, making variations only as required to use 3,3,3-trifluoro-2-hydroxy-2-methylpropionic acid in place of 4,4,4-trifluoro-2-methylbutyric acid to react with 6-piperazin-1-yl-pyridazine-3-carboxylic acid (3-methylbutyl)amide, the title compound was obtained as a white solid (55% yield). m.p. 181-183° C. ¹H NMR (300 MHz, CDCl₃) δ8.07, 7.98, 7.01, 4.86, 3.92-3.81, 3.55, 1.74, 1.51, 0.81-0.68, 0.46, 0.09. ¹³C NMR (75 MHz, CDCl₃) δ 167.2, 163.1, 160.0, 145.4, 127.1, 126.3, 122.5, 112.5. 76.8-75.6 (q, J=117 Hz, C-¹⁹F), 44.6, 39.7, 35.3, 20.5, 8.5, 4.8. MS (ES+) m/z 416 (M+1).

Example 15 Synthesis of 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide

To a solution of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide (58 mg, 0.24 mmol) in 10 mL of DMF was added 1,8-diazabicylco[5.4.0]undec-7-ene (0.109 g), piperazin-1-yl-(2-trifluoromethylphenyl)methanone (86.7 mg, 0.33 mmol) and Bu₄NI (4 mg, 0.01 mmol). The mixture was heated at 80° C. overnight. Water was added and the mixture was extracted with ethyl acetate (2×15 mL). The organic extract was washed with diluted HCl, followed by bicarbonate solution and brine, then dried over Na₂SO₄ and concentrated. The residue was dissolved in small amount of dichloromethane and purified by column chromatography eluted with ethyl acetate to yield the product as a white solid (35.5 mg, 32% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.24, 8.02, 7.73, 7.58, 7.34, 6.98, 4.04, 3.85, 3.52, 3.33, 3.10, 2.60-2.41, 0.95, 0.52, 0.32. MS (ES+) m/z 464.3 (M+1).

Example 15.1 4-methyl-2-({6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]-pyridazine-3-carbonyl}amino)pentanoic acid methyl ester

Following the procedure of Example 15, making variations only as required to use 2-[(6-chloropyridazine-3-carbonyl)amino]-4-methylpentanoic acid methyl ester in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)-methanone, the title compound was obtained as a white solid (36% yield). ¹H NMR (400 MHz, CDCl₃) δ 8.16, 8.04, 7.85, 7.66-7.53, 7.28, 7.00, 4.82-4.77, 4.14-3.68, 3.58-3.51, 1.83-1.60, 1.03-0.95.

Example 15.2 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid cyclopropylmethylamide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid cyclopropylmethylamide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a white solid (31% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.16-7.88, 7.75, 7.68-7.46, 7.18, 7.00, 4.17-3.64, 3.21-3.12, 1.07-1.00, 0.61-0.44, 0.26-0.20.

Example 15.3 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid [2-(4-methoxyphenyl)ethyl]amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid [2-(4-methoxyphenyl)ethyl]amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a white solid (12% yield). ¹H NMR (400 MHz, CDCl₃) δ 8.04, 7.93, 7.74, 7.63, 7.56, 7.36, 7.12, 6.92, 6.81, 4.08-3.46, 3.33, 2.87.

Example 15.4 6-[4-(2-trifluoromethylbenzoyl)-piperazin-1-yl]pyridazine-3-carboxylic acid (3-phenylpropyl)amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid (3-phenylpropyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a white solid (15% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.05, 7.93, 7.74, 7.63, 7.56, 7.39, 7.29-7.13, 6.92, 4.12-3.29, 2.68, 2.02-1.83.

Example 15.5 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid [2-(4-chlorophenoxy)ethyl]amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid [2-(4-chlorophenoxy)ethyl]amide in place of 6-chloro-pyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a white solid (13% yield). ¹H NMR (400 MHz, CDCl₃) δ 8.27, 8.05, 7.74, 7.64, 7.57, 7.37, 7.25-7.20, 7.00, 6.85-6.82, 4.02-3.32.

Example 15.6 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin E-3-carboxylic acid [2-(4-fluorophenoxy)ethyl]amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid [2-(4-fluorophenoxy)ethyl]amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)-methanone, the title compound was obtained as a white solid (49% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.28, 8.05, 7.74, 7.63, 7.56, 7.35, 7.03-6.92, 6.87-6.81, 4.02-3.30.

Example 15.7 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid [2-(2,4-difluorophenyl)ethyl]amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid [2-(2,4-difluorophenyl)ethyl]amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a white solid (33% yield). m.p. 179-181° C. ¹H NMR (400 MHz, CDCl₃) δ 8.04, 7.91, 7.75, 7.61, 7.37, 7.30-6.89, 4.09-3.66, 3.38-3.32, 2.88. MS (ES+) m/z 520 (M+1).

Example 15.8 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3,3-dimethylbutyl)amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid (3,3-dimethylbutyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a white solid (17% yield). ¹H NMR (400 MHz, CDCl₃) δ 8.05, 7.83-7.72, 7.64, 7.57, 7.38, 6.98, 4.09-3.66, 3.50-3.45, 3.37-3.34, 1.57-1.52, 0.96. MS (ES+) m/z 464.6 (M+1).

Example 15.9 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-phenylcyclopropylmethyl)amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid (2-phenylcyclopropylmethyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a white solid (25% yield). ¹H NMR (400 MHz, CDCl₃) δ 8.09-8.03, 7.76, 7.64, 7.57, 7.36, 7.28-7.21, 7.17-7.12, 7.07-6.96, 4.09-3.32, 1.92-1.86, 1.47-1.38, 1.01-0.96. MS (ES+) m/z 510.4 (M+1).

Example 15.10 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-cyclopropylpropyl)amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid (3-cyclopropylpropyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a white solid (28% yield). ¹H NMR (400 MHz, CDCl₃) δ 8.04, 7.89, 7.73, 7.65, 7.58, 7.38, 6.99, 4.08-3.67, 3.54-3.46, 3.39-3.31, 1.77-1.66, 1.34-1.23, 0.72-0.62, 0.45-0.36, 0.06-0.04. MS (ES+) m/z 462.2 (M+1).

Example 15.11 4-[6-(2-cyclopropylethylcarbamoyl)pyridazin-3-yl]piperazine-1-carboxylic acid T-butyl ester

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid (2-cyclopropylethyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazine-1-carboxylic acid t-butyl ester, the title compound was obtained as a white solid (47% yield). ¹H NMR (400 MHz, CDCl₃) δ 8.04-7.95, 6.97, 3.62-3.54, 1.59-1.44, 1.34-1.23, 0.72-0.62, 0.45-0.36, 0.06-0.04. MS (ES+) m/z 376.3 (M+1).

Example 15.12 6-[4-(tetrahydrofuran-2-carbonyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid (2-cyclopropylethyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(tetrahydrofuran-2-yl)methanone, the title compound was obtained as a white solid (47% yield). ¹H NMR (400 MHz, CDCl₃) δ 8.12-7.88, 6.97, 4.64-4.60, 3.93-3.42, 2.56-2.35, 2.10-1.93, 1.52-1.38, 0.84-0.62, 0.50-0.38, 0.17-0.05. MS (ES+) m/z 374.3 (M+1).

Example 15.13 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin e-3-carboxylic acid [2-(3-fluorophenyl)ethyl]amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid [2-(3-fluorophenyl)ethyl]amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a white solid (71% yield). ¹H NMR (400 MHz, CDCl₃) δ 8.05, 7.93, 7.74, 7.64-7.56, 7.37-7.35, 7.26-7.24, 7.01-6.90, 4.10-4.03, 3.89-3.70, 3.36-3.33, 2.92.

Example 15.14 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid [2-(4-fluorophenyl)ethyl]amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid [2-(4-fluorophenyl)ethyl]amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (59.8% yield). ¹H NMR (400 MHz, CDCl₃) δ 8.05, 7.92, 7.72-7.76, 7.66-7.54, 7.38-7.34, 7.20-7.14, 7.0-6.94, 4.10-4.02, 3.92-3.84, 3.80-3.68, 3.37-3.36, 2.90.

Example 15.15 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid [2-(2-fluorophenyl)ethyl]amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid [2-(2-fluorophenyl)ethyl]amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (70.7% yield). ¹H NMR (400 MHz, CDCl₃) δ 8.04, 7.95, 7.75-7.72, 7.63, 7.55, 7.36, 7.22-7.15, 7.05-6.97, 4.07-4.02, 3.89-3.83, 3.79-3.67, 3.35-3.32, 2.96.

Example 15.16 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid [2-(4-chlorophenyl)ethyl]amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid [2-(4-chlorophenyl)ethyl]amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a light yellow powder (46.5% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.10, 7.95, 7.75, 7.65, 7.58, 7.35, 7.25, 7.15, 7.00, 4.10, 3.95-3.66, 3.38, 2.90.

Example 15.17 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid [2-(3-chlorophenyl)ethyl]amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid [2-(3-chlorophenyl)ethyl]amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a light yellow powder (59.6% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.05, 7.94, 7.75, 7.64, 7.57, 7.37, 7.26, 7.24-7.19, 7.12, 7.00, 4.10, 3.95-3.66, 3.38, 2.90.

Example 15.18 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-phenylpropyl)amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid (2-phenylpropyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (63.2% yield). ¹H NMR (500 MHz, CDCl₃) δ 7.97, 7.80, 7.68, 7.57, 7.50, 7.30, 7.24, 7.20-7.12, 6.92, 3.98, 3.80, 3.74-3.60, 3.53, 3.28, 3.00, 1.28.

Example 15.19 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-biphenyl-4-yl-ethyl)amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid (2-biphenyl-4-yl-ethyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (63.2% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.07, 7.98, 7.76, 7.64, 7.60-7.52, 7.44, 7.38-7.30, 7.00, 4.06, 3.88, 3.82-3.68, 3.36, 2.98.

Example 15.20 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid (3-methylbutyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (63.2% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.05, 7.98, 7.75, 7.64, 7.57, 7.37, 7.00, 4.06, 3.89, 3.82-3.64, 3.49, 3.36, 1.70, 1.50, 0.95.

Example 15.21 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (4-hydroxybutyl)amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid (4-hydroxybutyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (30% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.05, 7.98, 7.75, 7.63, 7.57, 7.37, 6.99, 4.06, 3.88, 3.82-3.67, 3.52, 3.36, 1.70.

Example 15.22 (R)-6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-hydroxy-2-phenylethyl)amide

Following the procedure of Example 15, making variations only as required to use (R)-6-chloropyridazine-3-carboxylic acid (2-hydroxy-2-phenylethyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (64.5% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.28, 8.05, 7.76, 7.64, 7.58, 7.44-7.32, 7.29, 7.00, 4.96, 4.08, 3.92-3.68, 3.61, 3.36.

Example 15.23 (S)-6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-hydroxy-2-phenylethyl)amide

Following the procedure of Example 15, making variations only as required to use (S)-6-chloropyridazine-3-carboxylic acid (2-hydroxy-2-phenylethyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (64.5% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.28, 8.05, 7.76, 7.64, 7.58, 7.44-7.32, 7.29, 7.00, 4.96, 4.08, 3.92-3.68, 3.61, 3.36. MS (ES+) m/z 500 (M+1).

Example 15.24 4-({6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carbonyl}amino)butyric acid ethyl ester

Following the procedure of Example 15, making variations only as required to use 2-[(6-chloropyridazine-3-carbonyl)amino]butyric acid ethyl ester in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (37.8% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.05, 7.96, 7.75, 7.65, 7.57, 7.37, 7.00, 4.16-4.04, 3.92-3.70, 3.56, 3.36, 2.40, 1.25. MS (ES+) m/z 494 (M+1).

Example 15.25 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-hydroxy-4,4-dimethylpentyl)amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid (3-hydroxy-4,4-dimethylpentyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (39% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.18, 8.05, 7.74, 7.63, 7.56, 7.36, 6.99, 4.05, 3.92-3.67, 3.45-3.32, 3.26, 1.76, 1.55, 0.88. MS (ES+) m/z 494 (M+1).

Example 15.26 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-hydroxy-3-methylbutyl)amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid (3-hydroxy-3-methylbutyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (46.4% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.30, 8.05, 7.75, 7.65, 7.57, 7.37, 6.98, 4.06, 3.88, 3.81-3.69, 3.64, 3.40-3.32, 1.80, 1.64, 1.30. MS (ES+) m/z 466 (M+1).

Example 15.27 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-ethoxyethyl)amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid (2-ethoxyethyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (24.8% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.18, 8.07, 7.76, 7.65, 7.58, 7.38, 7.00, 4.07, 3.90, 3.83-3.65, 3.60, 3.52, 3.36, 1.20. MS (ES+) m/z 452 (M+1).

Example 15.28 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid pentylamide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid pentylamide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a white solid (94% yield). m.p. 123-125° C. ¹H NMR (300 MHz, CDCl₃) δ 8.03, 7.85, 7.62, 7.54, 7.35, 6.97, 4.06-3.99, 3.91-3.69, 3.44, 3.33, 1.62-1.55, 1.37-1.33, 0.95-0.81. ¹³C NMR (75 MHz, CDCl₃) δ 167.6, 162.9, 160.0, 145.5, 132.4, 129.5, 127.2, 127.1, 126.9-127.8, 112.5, 77.2, 46.4, 44.6, 44.4, 41.3, 39.4, 29.3, 29.1, 22.4, 14.0. MS (ES+) m/z 450.2 (M+1), 472.2 (M+Na).

Example 15.29 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-hydroxy-3,3-dimethylbutyl)amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid (2-hydroxy-3,3-dimethylbutyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a brown solid (75% yield). m.p. 236-240° C. ¹H NMR (300 MHZ, CDCl₃) δ 7.90, 7.83-7.79, 7.75-7.73, 7.69-7.65, 7.54-7.52, 7.30, 4.29, 3.91-3.73, 3.43-3.32, 3.20-3.11, 2.81, 2.77, 0.95. MS (ES+) m/z 480 (M+1).

Example 15.30 6-[4-(5-Fluoro-2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-hydroxy-3,3-dimethylbutyl)amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid (2-hydroxy-3,3-dimethylbutyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(5-fluoro-2-trifluoromethylphenyl)methanone, the title compound was obtained as a brown solid (51% yield). m.p.: 186-189° C. ¹H NMR (300 MHz, CDCl₃) δ8.20, 8.04, 7.75, 7.22, 7.07, 6.98, 4.06-3.98, 3.91-3.71, 3.47-3.23, 2.45, 0.96. ¹³C NMR (75 MHz, CDCl₃) δ 166.3, 164.1, 160.1, 160.0, 130.1, 127.2, 116.9, 116.6, 115.0, 114.7, 112.4, 79.4, 46.4, 44.5, 44.3, 41.9, 41.3, 34.4, 25.7. MS (ES+) m/z 498 (M+1).

Example 15.31 6-[4-(2-methylcyclopropanecarbonyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid (2-cyclopropylethyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-methylcyclopropyl)methanone, the title compound was obtained as a white solid (88% yield). ¹³C NMR (75 MHz, CDCl₃) δ 177.1, 163.5, 159.5, 144.9, 131.3, 126.4, 115.1, 49.7, 45.2, 39.5, 37.5, 37.2, 35.3, 34.6, 29.9, 28.5, 26.5, 23.4, 8.6, 4.2. MS (ES+) m/z 360 (M+3).

Example 15.32 6-[4-(5-fluoro-2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid pentylamide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid pentylamide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(5-fluoro-2-trifluoromethylphenyl)methanone, the title compound was obtained as a white solid (31% yield). m.p. 162-164° C. ¹H NMR (300 MHz, CDCl₃) δ 8.05, 7.87, 7.24, 7.07, 6.99, 4.08-3.99, 3.90-3.66, 3.45, 3.35, 1.65-1.55, 1.37-1.30. ¹³C NMR (75 MHz, CDCl₃) δ 166.1, 162.9, 160.0, 145.7, 129.7, 127.2, 116.9, 116.6, 115.0, 114.7, 112.6, 77.2, 46.4, 44.6, 44.4, 41.3, 39.4, 29.3, 29.1, 22.4, 14.0.

Example 15.33 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (4-methylpentyl)amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid (4-methylpentyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a white solid (36% yield). m.p. 43-45° C. ¹H NMR (300 MHz, CDCl₃) δ 7.71, 7.66-7.52, 7.34, 6.96, 4.06-3.98, 3.87-3.68, 3.63, 3.53, 3.19, 3.25, 3.09, 1.65-1.58, 1.36-1.33, 1.26-1.12, 0.85. ¹³C NMR (75 MHz, CDCl₃) δ 167.6, 166.9, 166.2, 159.0, 158.9, 149.5, 149.4, 134.4, 132.4, 129.5, 129.2, 127.2, 126.9, 126.8, 112.6, 112.5, 51.4, 48.8, 46.4, 44.7, 44.4, 41.3, 37.8, 34.8, 34.0, 29.7, 29.0, 28.7, 27.1, 26.7, 22.5, 22.3, 14.0, 13.9. MS (ES+) m/z 464.2 (M+1), 486.2 (M+Na).

Example 15.34 6-[4-(5-fluoro-2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid (3-methylbutyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(5-fluoro-2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (28.3% yield). ¹H NMR (400 MHz, CDCl₃) δ8.05, 7.86, 7.78-7.75, 7.28-7.22, 7.12-7.08, 7.02, 4.08-4.01, 3.91-3.86, 3.82-3.68, 3.55-3.46, 3.38, 1.73-1.65, 1.56-1.48, 0.94.

Example 15.35 6-[4-(4-fluoro-2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid (3-methylbutyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(4-fluoro-2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (63.8% yield). ¹H NMR (400 MHz, CDCl₃) δ 8.08, 7.85, 7.48-7.46, 7.41-7.32, 7.02, 4.08-4.05, 3.95-3.88, 3.80-3.68, 3.52-3.45, 3.35, 1.73-1.68, 1.51, 0.94.

Example 15.36 6-[4-(2-fluoro-6-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid (3-methylbutyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(6-fluoro-2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (16.8% yield). ¹H NMR (400 MHz, CDCl₃) δ 8.06, 7.85, 7.57-7.55, 7.39-7.36, 7.01, 4.04-3.94, 3.86-3.79, 3.49, 3.44-3.36, 1.73-1.68, 1.52, 0.94.

Example 15.37 6-[4-(2,6-difluorobenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid (3-methylbutyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2,6-difluorophenyl)methanone, the title compound was obtained as a white powder (42.2% yield). ¹H NMR (400 MHz, CDCl₃) δ 8.07, 7.85, 7.44-7.38, 7.03-6.97, 4.0-3.99, 3.86-3.83, 3.52-3.48, 1.73-1.67, 1.51, 0.94.

Example 15.38 6-[4-(2,2,3,3-tetramethylcyclopropanecarbonyl)piperazin-1-yl]-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid (2-cyclopropylethyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2,2,3,3-tetramethylcyclopropyl)methanone, the title compound was obtained as a white solid (35% yield). ¹H NMR (400 MHz, CDCl₃) δ 8.07, 8.01, 7.01, 3.91-3.89, 3.81-3.65, 3.57, 1.21, 1.19, 0.79-0.072, 0.49-0.46, 0.11-0.10. MS (ES+) m/z 400 (M+1).

Example 15.39 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-methylcyclopropylmethyl)amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid (2-methylcyclopropylmethyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a white solid (26% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.06, 7.96, 7.75, 7.65, 7.58, 7.38, 7.01, 4.04-4.10, 3.86-3.93, 3.69-3.83, 3.25-3.42, 1.12, 1.05, 0.71-0.80, 0.64-0.72, 0.39-0.45, 0.25-0.30. MS (ES+) m/z 448 (M+1).

Example 15.40 4-[6-(3-methylbutylcarbamoyl)pyridazin-3-yl]piperazine-1-carboxylic acid T-butyl ester

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid (3-methylbutyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazine-1-carboxylic acid t-butyl ester, the title compound was obtained as a white solid (83% yield). ¹H NMR (500 MHz, CDCl₃) δ8.03, 7.86, 6.97, 3.75, 3.56-3.63, 3.49, 1.65-1.76, 1.52, 0.94. MS (ES+) m/z 378 (M+1).

Example 15.41 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclobutylethyl)amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid (2-cyclobutylethyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (47% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.02, 7.74, 7.73, 7.57, 7.35, 6.98, 4.03, 3.89-3.66, 3.40-3.31, 2.36, 2.09-2.00, 1.92-1.57. ¹³C NMR (75 MHz, CDCl₃) δ 167.6, 134.3, 132.4, 129.5, 127.2, 127.0, 126.9, 126.8, 126.7, 125.5, 121.8, 112.6, 46.4, 44.6, 44.5, 41.3, 37.6, 36.5, 33.7, 28.3, 18.6. MS (ES+) m/z 462.3 (M+1).

Example 15.42 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid hexylamide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid hexylamide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethyl-phenyl)methanone, the title compound was obtained as a white powder (35% yield). ¹H NMR (300 MHz, CDCl₃) δ8.02, 7.85, 7.72, 7.56, 7.34, 6.97, 4.00, 3.90-3.64, 3.48-3.28, 1.58, 1.29, 0.85. ¹³C NMR (75 MHz, CDCl₃) δ 167.6, 162.9, 160.0, 145.5, 134.3, 132.8, 129.5, 127.6, 127.2, 126.9, 125.4, 46.4, 44.6, 44.4, 41.3, 39.4, 31.5, 29.5, 26.6, 22.6, 14.0. MS (ES+) m/z (%) 464 (M+1).

Example 15.43 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-cyclobutylpropyl)amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid (3-cyclobutylpropyl)amide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethylphenyl)methanone, the title compound was obtained as a white powder (28% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.03, 7.85, 7.73, 7.57, 7.34, 6.99, 4.05, 3.89-3.65, 3.45, 3.33, 2.27, 1.99, 1.76, 1.58-1.39. ¹³C NMR (75 MHz, CDCl₃) δ 167.6, 162.8, 159.9, 145.4, 134.2, 132.4, 129.5, 127.2, 126.9, 126.7, 112.7, 46.4, 44.6, 44.5, 41.2, 39.4, 35.7, 34.1, 28.3, 27.2, 18.4. MS (ES+) m/z 475.9 (M+1).

Example 15.44 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid heptylamide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid heptylamide in place of 6-chloropyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide to react with piperazin-1-yl-(2-trifluoromethyl-phenyl)methanone, the title compound was obtained as a white powder (41% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.05, 7.85, 7.72, 7.58, 7.34, 6.98, 4.03, 3.94-3.64, 3.47-3.28, 1.58, 1.32-1.25, 0.84. ¹³C NMR (75 MHz, CDCl₃) δ 167.6, 162.9, 160.0, 145.5, 134.3, 132.4, 129.5, 126.9, 126.3, 125.4, 121.8, 112.6, 46.4, 44.5, 41.3, 39.4, 31.7, 29.6, 29.0, 26.9, 22.6, 14.1. MS (ES+) m/z 478.2 (M+1).

Example 15.45 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (4-cyclopropylbutyl)amide

Following the procedure of Example 15, making variations only as required to use 6-chloropyridazine-3-carboxylic acid (4-cyclopropylbutyl)amide in place of 6-chloropyridazine-3-carboxylic acid (3-cyclobutylpropyl)amide to react with piperazin-1-yl-(2-trifluoromethyl-phenyl)methanone, the title compound was obtained as a white powder (21% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.03, 7.86, 7.72, 7.58, 7.34, 6.98, 4.05, 3.89-3.62, 3.48-3.31, 1.64-1.41, 1.20, 0.60, 0.39-0.30, −0.04. ¹³C NMR (75 MHz, CDCl₃) δ 167.6, 162.9, 160.0, 145.4, 134.3, 132.4, 129.5, 127.2, 126.9, 126.7, 125.4, 121.8, 112.6, 46.4, 44.6, 44.4, 41.2, 39.5, 34.4, 29.4, 27.0, 10.7, 4.4. MS (ES+) m/z 476.1 (M+1).

Example 16 Synthesis of 4-methyl-2-({6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carbonyl}amino)pentanoic acid

Lithium hydroxide monohydride (25 mg, 0.595 mmol) was added to a solution of 4-methyl-2-({6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carbonyl}-amino)pentanoic acid methyl ester (130 mg, 0.256 mmol) in tetrahydrofuran (3 mL) and water (1.5 mL), the reaction mixture was stirred at ambient temperature for 3 hours, THE was removed by evaporation, the residue was adjusted with 5% citric acid to pH about 6, and diluted with ethyl acetate, washed with water and brine, dried (Na₂SO₄) and concentrated to afford 4-methyl-2-({6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carbonyl}amino)pentanoic acid (94 mg, 74%). ¹H NMR (400 MHz, CDCl₃) δ 8.17, 8.02, 7.78, 7.66-7.53, 7.38, 6.99, 6.72, 4.88-4.73, 4.25-3.60, 3.44-3.21, 1.79-1.06, 1.33-1.19, 1.03, 0.99.

Example 17 Synthesis of 6-{4-[1-(2-trifluoromethylphenyl)ethyl]piperazin-1-yl}-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide hydrochloride

Titanium isopropoxide (0.6 mL, 2.0 mmol) was added to a solution of 6-piperazin-1-yl-pyridazine-3-carboxylic acid 2-(cyclopropylethyl)amide (282 mg, 1.02 mmol) and 2-(trifluoromethyl)acetophenone (0.23 mL, 1.53 mmol) in THF (3 mL). The resulting mixture was stirred at ambient temperature for 4 hours. Sodium cyanoborohydride (130 mg, 1.96 mmol) was added, and stirring was continued for another 13 hours. Aqueous sodium hydroxide (2.0 mL, 1.0 M) was added. After stirred for 5 minutes at ambient temperature, the reaction mixture was diluted with ethyl acetate (50 mL), and then washed with water and brine. The organic layer was dried over anhydrous Na₂SO₄ and concentrated. Purification via flash chromatography afforded 6-{4-[1-(2-trifluoromethylphenyl)ethyl]piperazin-1-yl}-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide (126 mg). This product was dissolved in CH₂Cl₂ (2 mL) and HCl in ether (7 M, 0.2 mL, 1.4 mmol) was then added. This mixture was kept at ambient temperature for 2 hours. The white precipitate was collected by filtration and washed with ether and dried in vacuo to yield the title compound as a white solid (104 mg, 21% yield). m.p. 158-163° C. ¹H NMR (300 MHz, DMSO-d₆) δ 12.10, 8.81, 8.67, 7.90-7.81, 7.64, 7.40, 4.70-2.85, 1.69, 1.38, 0.72-0.58, 0.40-0.32, 0.023-0.02. MS (ES+) m/z 374.3 (M+1-HCl).

Example 18 Synthesis of 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-oxo-2-phenylethyl)amide

To a solution of 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-hydroxy-2-phenylethyl)amide (0.517 g, 1.03 mmol) in dichloromethane (10 mL), 1,1,1-triacetoxy-1,1-dihydro-1,2-benziodoxol-3(1H)-one (0.53 g) was added in one portion under stirring in a cold water bath. After stirred in a cold water bath for 15 minutes and then at ambient temperature for 2 hours, the reaction mixture was diluted with diethyl ether (20 mL). The mixture was poured into a solution of sodium thiosulfate (1.176 g, 7.44 mmol) in saturated aqueous sodium biocarbonate (29 mL). The mixture was extracted with ethyl acetate (100 mL). The organic layer was washed with saturated aqueous NaHCO₃ (2×15 mL) and water (2×15 mL). The combined aqueous washes were then extracted with ethyl acetate (2×80 mL). The combined organic phases were dried over Na₂SO₄ and filtered, the solvent was then removed in vacuo. The crude product was purified by column chromatography, which was sequentially eluted with hexane:ethyl acetate (1:1), hexane:ethyl acetate (1:2) and pure ethyl acetate. The product was obtained as a white powder (0.261 g, 51% yield). m.p. 196-198° C. ¹H NMR (300 MHz, CDCl₃) δ 8.72, 7.97-8.06, 7.74, 7.47-7.66, 7.36, 6.99, 4.96, 4.02-4.11, 3.70-3.92, 3.27-3.42. ¹³C NMR (CDCl₃) δ 193.4, 167.7, 163.4, 160.0, 145.1, 134.6, 134.2, 134.0, 132.4, 129.6, 128.9, 128.0, 127.2, 126.9, 126.8, 112.3, 46.4, 44.7, 44.4, 41.3. MS (ES+) m/z 498 (M+1).

Example 19 Synthesis of acetic acid 1-phenyl-2-({6-[4-(2-trifluoromethyl-benzoyl)piperazin-1-yl]pyridazine-3-carbonyl}amino)ethyl ester

To a solution of 6-[4-2-trifluoromethylbenzoylpiperazin-1-yl]pyridazine-3-carboxylic acid (2-hydroxy-2-phenylethyl)amide (50 mg, 0.1 mmol) in chloroform (2 mL), acetic anhydride (0.25 mL), triethylamine (0.25 mL) and 4-dimethylaminopyridine (18 mg) were added. After stirred at ambient temperature for 6 hours, the reaction mixture was diluted with ethyl acetate (100 mL), washed with water (3×10 mL) and dried over Na₂SO₄. The crude product obtained after removal of the solvent was purified by column chromatography eluted sequentially with hexane:ethyl acetate=1:1 and 1:2 to give a white powder (49.6 mg, 91.5% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.10, 8.04, 7.75, 7.65, 7.57, 7.40-7.28, 7.00, 5.92, 4.07, 3.98, 3.90, 3.82-3.68, 3.36, 2.10. MS (ES+) m/z 508 (M+1).

Example 19.1 Acetic Acid 1,1-dimethyl-3-({6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]-pyridazine-3-carbonyl}amino)propyl ester

Following the procedure of Example 19, making variations only as required to use 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-hydroxy-3-methylbutyl)amide in place of 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-hydroxy-2-phenylethyl)amide to react with acetic anhydride, the title compound was obtained as a white powder (80% yield). ¹H NMR (500 MHz, CDCl₃) δ 8.05, 8.01, 7.75, 7.65, 7.57, 7.37, 6.99, 4.06, 3.88, 3.81-3.67, 3.58, 3.36, 2.06, 2.01, 1.52. MS (ES+) m/z 508 (M+1).

Example 20 Synthesis of 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-methoxy-3,3-dimethylbutyl)amide

To a solution of 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-hydroxy-3,3-dimethylbutyl)amide (81.6 mg, 0.17 mmol) in THF (1.0 mL) was added sodium hydride (5.0 mg, 0.19 mmol), followed by methyl iodide (15 mL, 0.26 mmol). The reaction mixture was stirred at ambient temperature for 16 hours and then the solvent was removed. The gummy material was diluted with dichloromethane (5 mL), washed with water (2×2 mL), dried over MgSO₄ and filtered off the solid. After the solvent was concentrated into dryness, the crude material was subjected to column chromatography eluted sequentially with ethyl acetate:hexane (1:1) and ethyl acetate to obtain 25.3 mg (30%) of the product as solid. m.p. 65-68° C. ¹H NMR (300 MHz, CDCl₃) δ 7.73-7.69, 7.62, 7.53, 7.33, 6.98-6.93, 4.18-3.59, 3.48, 3.41, 3.37-3.26, 3.18, 3.03-2.98, 1.76, 0.98, 0.75. ¹³C NMR (75 MHz, CDCl₃) δ 167.6, 166.4, 158.9, 149.8, 149.3, 134.3, 132.4, 129.5, 129.4, 129.3, 129.1, 127.2, 126.9-126.7, 112.7, 88.1, 61.7, 61.4, 52.7, 52.0, 46.4, 44.7, 44.6, 44.5, 44.4, 41.3, 41.2, 40.5, 35.8, 35.3, 35.0, 26.0, 25.9, 25.7. MS (ES+) m/z 508 (M+1).

Example 21 Synthesis of 6-[3,5-dimethyl-4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

To a solution of 6-(3,5-dimethylpiperazin-1-yl)pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide (0.40 g, 1.33 mmol) in dichloromethane (15 mL) was added diisopropyl ethylamine (0.34 g, 0.46 mL, 2.66 mmol) followed by 2-trifluoromethylbenzoyl chloride (0.31 g, 0.22 mL, 1.46 mmol) at ambient temperature. The reaction solution was stirred for 16 hours and poured into cold water (10 mL). The organic layer was extracted with dichloromethane (50 mL) and washed with saturated solution of NaHCO₃ (2×10 mL) and dried over MgSO₄. After filtration, the filtrate was concentrated in vacuo. The crude material was purified by column chromatography eluting with ethyl acetate (100%) to obtain 0.18 g of colorless solid (28% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.03-7.91, 7.70, 7.63-7.49, 7.32, 6.99-6.95, 5.00, 4.39-4.22, 3.64, 3.55-3.47, 3.39-3.17, 1.51-1.38, 1.24-1.14, 0.76-0.67, 0.42, 0.05. ¹³C NMR (75 MHz, CDCl₃) δ 168.0, 163.0, 160.9, 144.9, 132.3, 131.9, 129.4, 129.3, 127.2, 127.0, 126.8, 111.5, 50.4, 49.1, 48.7, 48.5, 48.2, 45.5, 45.3, 39.6, 34.6, 20.2, 19.5, 8.6, 4.2.

Example 22 Synthesis of 6-[2,5-dimethyl-4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid pentylamide

To a mixture of 6-chloropyridazine-3-carboxylic acid pentylamide (304 mg, 1.00 mmol) in 2-propanol (12 mL) was added 2,5-dimethylpiperazine (1.37 g, 12.0 mmol). The reaction mixture was refluxed for 2 days. Another 0.25 g of 2,5-dimethylpiperazine and 1.0 mL of triethylamine were added to the reaction mixture and heating was continued for another 24 hours. After the reaction mixture was cooled to ambient temperature and the solvent was removed by rotary evaporator. To the dichloromethane solution of the crude material (20 mL) was added the solution of 2-trifluoromethylbenzoyl chloride (0.63 g, 3.00 mmol) in dichloromethane (20 mL) and the reaction mixture was stirred at ambient temperature for 16 hours. The organic layer was diluted with dichloromethane (50 mL) and then washed with 10% HCl, dried over MgSO₄. After filtration, the filtrate was concentrated in vacuo. The crude material was purified by column chromatography eluting with ethyl acetate (100%) to afford 300 mg (31% yield) of the product as a colourless solid. ¹H NMR (300 MHz, CDCl₃) δ 7.74-7.43, 7.36-7.24, 5.17-5.04, 4.91-4.79, 4.52, 4.52, 3.68-3.57, 3.54-3.44, 3.39-3.11, 2.93, 2.85-2.71, 1.36-1.31, 1.27-1.15, 1.23-1.05.

Example 23 Synthesis of 2-{4-[6-(2-cyclopropylethylcarbamoyl)pyridazin-3-yl]piperazine-1-carbonyl}benzoic acid

Lithium hydroxide monohydrate (0.066 g, 1.57 mmol) was added to a solution of 2-{4-[6-(2-cyclopropylethylcarbamoyl)pyridazin-3-yl]piperazine-1-carbonyl}benzoic acid methyl ester (0.230 g) in tetrahydrofuran (10 mL) and water (5 mL) stirred at ambient temperature overnight. THF was removed in vacuo, the residue was dissolved in ethyl acetate (100 mL), neutralized by addition of 5% HCl solution, washed with brine, dried over anhydrous Na₂SO₄ and concentrated. The residue was recrystallized from dichloromethane and hexanes to yield 0.107 g of the title compound (42% field). ¹H NMR (300 MHz, CDCl₃) δ 8.67, 9.07-7.87, 7.54, 7.41, 7.26-7.24, 6.95, 4.12-3.27, 1.55-1.40, 0.77-0.64, 0.50-0.34, 0.13-0.01; ¹³C NMR (75 MHz, CDCl₃) δ 170.7, 168.2, 163.2, 159.9, 145.0, 137.7, 133.1, 131.2, 129.2, 127.9, 127.2, 126.6, 112.6, 46.2, 44.1, 41.4, 39.7, 34.4, 8.6, 4.2; MS (ES+) m/z 424.2 (M+1).

Example 24 synthesis of 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid 2,2-(dimethylcyclopropylmethyl)amide

To a solution of 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (1.00 mmol) in dichloromethane (20 mL) was added diisopropylethylamine (0.8 mL, 4.60 mmol), 1-hydroxybenzotriazole hydrate (0.203 g, 1.50 mmol) and 1-(3-dimethylamino-propyl)-3-ethylcarbodiimide hydrochloride (0.384 mg, 2.00 mmol). The resulting mixture was stirred for 15 min, then 2,2-(dimethylcyclopropyl)methylamine (0.149 mg, 1.5 mmol) was added. The stirring was continued for another 24 h. The reaction mixture was diluted with dichloromethane (100 mL), washed sequentially with water and brine, then dried over anhydrous Na₂SO₄ and concentrated.

Purification by flash chromatography over silica gel (ethyl acetate) and recrystallization from ethyl acetate and hexanes afforded the title compound (0.089 g, 19%). m.p. 132-134° C. ¹H NMR (300 MHz, CDCl₃) δ 8.06-8.02, 1.90-7.80, 7.75, 7.64-7.52, 7.34, 6.98, 4.05-3.33, 1.11, 1.04, 0.89-0.79, 0.50-0.46, 0.16-0.13; ¹³C NMR (75 MHz, CDCl₃) δ 167.6, 162.7, 159.9, 145.4, 134.2, 132.3, 129.5, 127.2, 126.8, 125.4, 121.8, 112.5, 46.3, 44.6, 44.4, 40.5, 27.1, 23.5, 19.9, 18.7, 15.9; MS (ES+) m/z 462 (M+1).

Example 24.1 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-thiophen-2-yl-ethyl)amide

Following the procedure of Example 24, making variations only as required to use 2-thiophen-2-yl-ethylamine in place of 2,2-(dimethylcyclopropyl)methylamine to react with 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid, the title compound was obtained as a white powder (40% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.01, 7.73, 7.58, 7.34, 7.12, 6.98, 6.90, 6.84, 4.03, 3.89-3.55, 3.33, 3.12. ¹³C NMR (75 MHz, CDCl₃) δ 167.6, 163.1, 160.0, 145.2, 141.1, 134.2, 132.4, 129.5, 127.2, 127.0, 126.9, 125.3, 123.9, 121.8, 112.5, 46.4, 44.6, 44.4, 41.3, 40.9, 30.9. MS (ES+) m/z 490.0 (MeI).

Example 24.2 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (6-chloropyridazin-3-yl)amide

Following the procedure of Example 24, making variations only as required to use 3-amino-6-chloropyridazine in place of 2,2-(dimethylcyclopropyl)methylamine to react with 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid, the title compound was obtained as a white powder (8% yield). ¹H NMR (300 MHz, CDCl₃) δ 10.75, 8.62, 8.06, 7.75-7.50, 7.36, 7.03, 4.12-3.76, 3.36. C NMR (75 MHz, CDCl₃) δ 167.7, 162.2, 160.1, 154.0, 152.3, 143.8, 134.1, 132.4, 129.7, 129.6, 127.3, 127.2, 126.94, 126.88, 126.7, 120.7, 112.2, 46.3, 44.6, 44.3, 41.3. MS (ES+) m/z 492.1 (M+1).

Example 25 Synthesis of 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropyl-2-oxoethyl)amide

Dess-Martin periodinane (0.55 g, 1.3 mmol) was added to a solution of 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropyl-2-hydroxyethyl)amide (0.50 g, 1.07 mmol), the resulting reaction mixture was stirred at ambient temperature for 2 h, then diluted with ethyl acetate, sequentially washed with 10% Na₂S₂O₃ solution, saturated NaHCO₃ and brine. The organic layer was dried over anhydrous Na₂SO₄ and concentrated. The residue was purified by flash chromatography and recrystallized from ethyl acetate-hexanes to give the title compound in 87% yield (0.43 g). ¹H NMR (300 MHz, CDCl₃) δ 8.45-8.41, 8.02, 7.72, 7.63-7.51, 7.34, 7.00, 4.48, 4.47-3.28, 2.00-1.94, 1.18-1.11, 1.10-0.82. ¹³C NMR (75 MHz, CDCl₃) δ 204.4, 167.6, 163.1, 159.8, 144.9, 134.2, 132.3, 129.5, 129.0, 127.5, 127.2, 126.9, 121.8, 118.1, 112.4, 49.5, 46.3, 44.6, 44.4, 41.2, 18.7, 11.4. MS (ES+) m/z 462.0 (M+1).

Example 26 Synthesis of 6-[4-(2-sulfamoylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide

To an ice-cold solution of 6-[4-(2-methanesulfonylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide (0.078 g, 0.17 mmol) in 5 mL of THF cooled was added methyl magnesium chloride (0.071 mL, 0.212 mmol). The resulting mixture was stirred for 15 minutes at 0° C., and then 30 minutes at ambient temperature. The reaction mixture was cooled to 0° C. again, then tributylborane (0.255 mL, 0.255 mmol) was added. The mixture was stirred at ambient temperature for 30 minutes, then heated to reflux for 18 h. After the mixture was cooled to 0° C., sodium acetate, water and hydroxylamine-o-sulfonic acid (0.067 g) were added. The mixture was stirred for 3 h, and then diluted with ethyl acetate, washed with saturated sodium bicarbonate, brine, dried and concentrated in vacuo. The residue was purified by flash column chromatography using 20% methanol in ethyl acetate to yield the title product (0.033 g, 42% yield). ¹H NMR (300 MHz, CDCl₃) δ 8.58, 7.98, 7.81, 7.75-7.68, 7.64-7.58, 7.43, 7.19, 4.03-3.88, 3.78-3.59, 3.21-3.20, 3.152-3.147, 1.65-1.50, 1.46-1.35, 0.85. ¹³C NMR (75 MHz, CDCl₃) δ 170.1, 165.5, 161.7, 146.3, 139.1, 137.3, 135.5, 131.3, 130.9, 128.8, 127.9, 114.4, 45.6, 45.2, 44.96, 42.6, 39.5, 38.8, 27.1, 22.9. MS (ES+) m/z 460.1 (M+1).

Example 27 Synthesis of 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (4-chlorophenyl)amide

2-Chloro-4,6-dimethoxy-1,3,5-triazine (0.105 g, 0.60 mmol) was added to a cooled (0° C.) solution of 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (0.190 g, 0.50 mmol) and methylmorpholine (0.07 mL, 0.63 mmol) in THF (10 mL). The reaction mixture was stirred at 0° C. for 15 min, and then at ambient temperature for 1 h. 4-Chloroaniline (0.0765 g, 0.60 mmol) was then added. After stirring at ambient temperature for 20 h, the reaction mixture was diluted with ethyl acetate (100 mL), washed with water, brine, dried over anhydrous Na₂SO₄ and concentrated. Purification by flash chromatography and recrystallization from ethyl acetate/hexanes afforded the title compound in 67% yield (0.164 g). ¹H NMR (300 MHz, CDCl₃) δ 9.79, 8.08, 7.82-7.55, 7.36-7.28, 7.02, 4.10-4.00, 3.93-3.68, 3.35. ¹³C NMR (75 MHz, CDCl₃) δ 167.6, 160.7, 160.0, 144.8, 136.2, 134.2, 132.4, 129.5, 129.2, 129.1, 127.2, 126.9, 126.8, 126.7, 125.4, 121.8, 120.7, 112.6, 46.3, 44.5, 44.3, 41.2. MS (ES+) m/z 490.1 (M+1).

Example 27.1 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (5-chloropyridin-2-yl)amide

Following the procedure of Example 27, making variations only as required to use 2-amino-5-chloropyridine in place of 4-chloroaniline, the title compound was obtained as a white powder (36% yield). ¹H NMR (300 MHz, CDCl₃) δ 10.32, 8.32, 8.27, 8.08, 7.83-7.47, 7.36, 7.02, 4.11-4.03, 3.92-3.71, 3.36. ¹³C NMR (75 MHz, CDCl₃) δ 167.6, 161.4, 160.0, 149.4, 146.9, 144.4, 137.8, 134.1, 132.4, 129.5, 127.2, 126.9, 126.8, 126.7, 125.4, 121.8, 114.5, 112.2, 46.3, 44.5, 44.3, 41.2. MS (ES+) m/z 491.0 (M+1).

Example 27.2 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2,2-difluoro-2-pyridin-2-ylethyl)amide

Following the procedure of Example 27, making variations only as required to use 2,2-difluoro-2-pyridin-2-ylethylamine in place of 4-chloroaniline, the title compound was obtained as a white powder (49%). ¹H NMR (300 MHz, CDCl₃) δ 8.65, 8.27, 8.01, 7.81-7.46, 7.38-7.32, 6.96, 4.43-4.31, 4.12-3.64, 3.32. ¹³C NMR (75 MHz, CDCl₃) δ 167.6, 163.3, 159.9, 153.4, 153.1, 149.4, 144.8, 137.2, 134.2, 132.3, 129.5, 127.4, 127.2, 126.9, 126.8, 126.7, 126.3, 125.4, 125.2, 121.95, 121.81, 120.6, 120.5, 118.7, 115.5, 112.4, 46.3, 44.5, 44.4, 43.4, 43.0, 42.6, 41.2; MS (ES+) m/z 521.2 (M+1).

Example 27.3 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2,2-difluoro-2-phenylethyl)amide

Following the procedure of Example 27, making variations only as required to use 2,2-difluoro-2-phenylethylamine in place of 4-chloroaniline, the title compound was obtained as a white powder (53%). ¹H NMR (300 MHz, CDCl₃) δ 8.17, 8.00, 7.71, 7.64-7.50, 7.41-7.27, 6.97, 4.17-4.01, 3.89-3.66, 3.33. ¹³C NMR (75 MHz, CDCl₃) δ 167.6, 163.2, 159.9, 144.6, 134.6, 134.1, 132.3, 130.3, 129.5, 128.5, 127.3, 127.2, 126.8, 125.3, 121.8, 120.3, 117.1, 112.4, 46.3, 45.3, 44.5, 44.3; MS (ES+) m/z 520.2 (M+1).

Example 27.4 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid [2-(3-fluorophenyl)-2-hydroxyethyl]amide

Following the procedure of Example 27, making variations only as required to use 2-amino-1-(3-fluorophenyl)ethanol in place of 4-chloroaniline, the title compound was obtained as a white powder (34%). m.p. 117-119° C. ¹H NMR (300 MHz, CDCl₃) δ 8.25, 8.98, 7.72, 7.64-7.52, 7.35-7.23, 7.14-7.10, 6.97-6.78, 4.93, 4.05-3.31, 3.31. ¹³C NMR (75 MHz, CDCl₃) δ 167.6, 164.5, 164.3, 161.3, 159.9, 144.8, 144.6, 144.5, 134.1, 132.3, 130.0, 129.9, 129.5, 127.5, 127.2, 127.1, 126.9, 126.8, 126.7, 125.4, 121.8, 121.4, 114.7, 114.4, 113.0, 112.7, 112.4, 73.1, 47.5, 47.0, 46.3, 44.5, 44.3, 41.2; MS (ES+) m/z 518.3 (M+1).

Example 28 Synthesis of 6-[4-(2-trifluoromethylbenzoyl) piperazin-1-yl]pyridazine-3-carboxylic acid pyridin-2-ylamide

To a solution of 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (0.400 g, 1.052 mmol) was added DMF (0.03 mL) and thionyl chloride (0.5 mL). The reaction mixture was refluxed at 70° C. for 17.5 h. The mixture was evaporate d and the residue was dried overnight. The dried residue was dissolved in dichloromethane (8 mL) as an acid chloride stock solution for the next step reaction.

To a solution of 2-aminopyridine (0.038 g, 0.395 mmol) and triethylamine (0.1 mL) in dichloromethane (2 mL) was added above acid chloride stock solution (0.1315 M, 2 mL, 0.263 mmol) dropwise at ambient temperature. The reaction mixture was stirred at ambient temperature for 4 h and then diluted with ethyl acetate (100 mL), washed sequentially with water and brine. The organic layer was dried over Na₂SO₄ and evaporated. The crude product was purified by column chromatography to afford the title compound in 37% yield (0.044 g). ¹H NMR (300 MHz, CDCl₃) δ 10.30, 8.35, 8.09, 7.75-6.69, 7.65-7.52, 7.35, 7.09-6.96, 4.10-4.02, 3.92-3.71, 3.35. ¹³C NMR (75 MHz, CDCl₃) δ 167.7, 161.5, 160.1, 151.1, 148.3, 144.8, 138.2, 134.2, 132.4, 129.6, 127.2, 126.9, 126.8, 125.5, 121.8, 119.9, 114.0, 112.2, 46.4, 44.6, 44.3, 41.3. MS (ES+) m/z 457.3 (M+1).

Example 28.1 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid pyridazin-3-ylamide

Following the procedure of Example 28, making variations only as required to use pyridazin-3-ylamine in place of 2-aminopyridine to react with 6-[4-(2-trifluoromethylbenzoyl)-piperazin-1-yl]pyridazine-3-carbonyl chloride, the title compound was obtained as a white powder (17.3% yield). ¹H NMR (300 MHz, CDCl₃) δ 10.81, 9.05, 8.70, 8.13, 7.87-7.57, 7.39, 6.95, 4.16-3.80, 3.40. C NMR (300 MHz, CDCl₃) δ 167.7, 162.3, 160.1, 148.6, 144.1, 132.4, 129.6, 128.1,

Example 28.2 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-pyridin-2-ylethyl)amide

Following the procedure of Example 28, making variations only as required to use 2-pyridin-2-ylethylamine in place of 2-aminopyridine to react with 6-[4-(2-trifluoromethyl-benzoyl)piperazin-1-yl]pyridazine-3-carbonyl chloride, the title compound was obtained as a white powder (30%). m.p. 151-154° C. ¹H NMR (300 MHz, DMSO-d₆) δ 9.07, 8.78, 8.43, 7.99-7.61, 7.52, 7.34, 3.79-3.60, 3.35-3.14. MS (ES+) m/z 485.3 (M+1).

Example 29 Synthesis of 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (benzo[1,3]dioxol-5-yl-methyl)amide

A. A solution of 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (0.300 g, 0.789 mmol) in dichloromethane (12 mL) and THF (6 mL) was cooled to 0° C. N-Methylmorpholine (0.806 g, 0.789 mmol) was charged, followed by dropwise addition of isobutyl chloroformate (0.109 g, 0.789 mmol). After stirred at 0° C. for 20 min and at ambient temperature for 1.5 h, the mixture was evaporated. The residue was dissolved in dichloromethane (60 mL) and the solution was cooled down to 0° C. Water (5 mL) was added to the solution at stirring. The mixture was soon transferred into a 100 mL separation funnel. After quickly separated from water, the organic layer was evaporated at 10° C. The dry residue was then dissolved in dry dichloromethane (15 mL) and ready for next step reaction.

B. To the above mixed anhydride stock solution (0.053 M, 5 mL, 0.263 mmol) was added a solution of piperonylamine in dichloromethane (0.5 M, 0.52 mL, 0.26 mmol) drop wise at ambient temperature in 5 min. The reaction was stirred at ambient temperature for 16 h. The mixture was evaporated and dried under reduced pressure to give the title compound in 93% yield (0.136 g).

Example 30 Synthesis of 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (pyridin-2-yl-methyl)amide

A mixture of 6-[4-(2-Trifluoromethylbenzoyl 1 piperazin-1-yl]pyridazine-3-carboxylic acid methyl ester (0.099 g, 0.25 mmol), pyridin-2-yl-methylamine (0.7 mL) and sodium cyanide (0.245 g, 0.5 mmol) was stirred at ambient temperature overnight and purified by column chromatography to yield the title compound in 48% yield (0.057 g). m.p. 179-181° C. ¹H NMR (300 MHz, CDCl₃) δ 8.81, 8.59, 8.12, 7.78-7.50, 7.37, 7.21-7.13, 6.93, 4.83, 4.17-3.66, 3.37. ¹³C NMR (75 MHz, CDCl₃) δ 167.6, 163.3, 160.0, 156.5, 149.0, 145.3, 137.0, 134.2, 132.4, 129.5, 127.2, 122.5, 121.9, 112.3, 46.4, 44.6, 44.4, 41.3. MS (ES+) m/z 471 (M+1).

Example 30.1 6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-benzo[1,3]dioxol-5-yl-ethyl)amide

Following the procedure of Example 30, making variations only as required to use 2-benzo[1,3]dioxol-5-ylethylamine in place of pyridin-2-ylmethylamine, the title compound was obtained as a white powder (99%). m.p. 162-164° C. ¹H NMR (300 MHz, CDCl₃) δ 8.02, 7.89, 7.72, 7.64-7.51, 7.34, 6.97, 6.72-6.63, 5.89, 4.10-3.63, 3.34-3.31, 2.81. C30 NMR (75 MHz, CDCl₃) δ 167.6, 163, 159.9, 147.7, 146.1, 145.2, 134.2, 132.4, 132.3, 129.5, 127.2, 127.1, 126.9, 126.8, 126.7, 121.6, 112.4, 109.0, 108.4, 100.8, 46.3, 44.5, 44.4, 41.2, 40.8, 35.5. MS (ES+) m/z 528.2 (M+1).

Example 31 Synthesis of 6-[4-(2-trifluoromethylthiobenzoyl)piperazin-1-yl]-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

A. A mixture of 4-(2-trifluoromethylbenzoylpiperazin-1-carboxylic acid tert-butyl ester (3.58 g, 10.0 mmol) and Lawesson's reagents (2.12 g, 5.2 mmol) in toluene was heated to reflux for 4 h, and then concentrated. The residue was purified by flash column chromatography to yield 4-(2-trifluoromethylthiobenzoyl)piperazine-1-carboxylic acid tert-butyl ester (2.87 g, 76%). ¹H NMR (300 MHz, CDCl₃) δ 7.64, 7.54, 7.42, 7.21, 4.53-4.45, 4.27-4.19, 3.71-3.25, 1.42.

B. A solution of 4-(2-trifluoromethylthiobenzoyl)piperazine-1-carboxylic acid tert-butyl ester (2.1 g, 5.61 mmol) in dichloromethane and trifluoroacetic acid (30 mL, 2:1) was stirred at ambient temperature overnight, the solvents were removed by evaporation. The residue was dissolved in ethyl acetate, and washed with aqueous saturated NaHCO₃ and brine, dried over anhydrous Na₂SO₄ and concentrated to give piperazin-1-yl-(2-trifluoromethylphenyl)methanethione (1.47 g, 5.36 mmol) which was used directly for next step without further purification.

C. A mixture of piperazin-1-yl-(2-trifluoromethylphenyl)methanethione (1.1 g, 4.0 mmol), 6-chloropyridazine-3-carboxylic acid (2-cyclopropylethyl)amide (0.98 g, 3.98 mmol), K₂CO₃ (0.83 g, 6.0 mmol) and n-Bu₄NI (0.010 g) in dioxane (10 mL) was heated to reflux for 21 h, and then concentrated. The residue was purified by column chromatography and recrystallization from ethyl acetate and hexanes to afford the title compound in 76% yield (1.42 g). m.p. 117-120° C. ¹H NMR (300 MHz, CDCl₃) δ 8.05-7.93, 7.65, 7.55, 7.44, 7.24, 6.98, 4.61-4.40, 3.98-3.40, 1.51-1.47, 0.73-0.64, 0.44-0.35, 0.07-0.01. ¹³C NMR (75 MHz, CDCl₃) δ 197.0, 162.8, 159.6, 145.6, 140.2, 132.4, 128.8, 127.2, 127.0, 126.9, 125.5, 124.8, 124.4, 124.0, 121.8, 112.5, 50.4, 47.6, 44.2, 43.6, 40.0, 39.6, 34.4, 8.6, 4.2. MS (ES+) m/z 464.0 (M+1).

Example 32

The following compounds are synthesized by the synthetic processes as described above.

-   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2-phenoxyethyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid [3-(4-fluorophenyl)propyl]amide; -   1-[1-(4-Fluorophenyl)ethyl]-3-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}urea; -   1-[3-(4-Fluorophenyl)propyl]-3-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}urea; -   3-Cyclopentyl-N-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazin-3-yl}propionamide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid phenethylamide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (5-trifluoromethylpyridin-2-yl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (4-carbamoylphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (3-carbamoylphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid m-tolylamide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid p-tolylamide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid o-tolylamide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2-propylphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]-pyridazine-3-carboxylic     acid (4-propylphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (4-isopropylphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2-isopropylphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2-chloro-phenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2-cyano-3-fluorophenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2,4-dimethylphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2,5-dimethylphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2,6-dimethylphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2,3-dimethylphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (3,5-dimethylphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoylpiperazin-1-yl]pyridazine-3-carboxylic     acid (3,4-dimethyl-phenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (4-ethyl-phenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2-ethyl-phenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (3-fluoro-2-methylphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2-fluoro-4-methylphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (4-fluoro-2-methylphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2-fluoro-5-methylphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (3-fluoro-5-methylphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (3-fluoro-phenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2-fluoro-phenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (4-fluoro-phenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2,4-difluorophenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2,5-difluorophenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (3,4-difluorophenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2,3-difluorophenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2,6-difluorophenyl)amide; -   6-[4-(2-Trifluoromethylbenzoylpiperazin-1-yl]pyridazine-3-carboxylic     acid (7H-purin-6-yl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid pyrazin-2-ylamide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid indan-1-ylamide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (1H-tetrazol-5-yl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2H-[1,2,4]triazol-3-yl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (3-methyl-isoxazol-5-yl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (5-methyl-isoxazol-3-yl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (1H-pyrazol-3-yl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (5-methyl-1H-pyrazol-3-yl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid pyrimidin-2-ylamide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid pyrazin-2-ylamide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (4-methyl-pyrimidin-2-yl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2-oxo-2,3-dihydropyrimidin-4-yl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (6-oxo-1,6-dihydropyrimidin-2-yl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2-oxo-1,3-diazabicyclo[3.1.0]hex-3-en-4-yl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (5-oxo-4,5-dihydro-1H-pyrazol-3-yl)amide, -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid [1,3,4]thiadiazol-2-ylamide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid thiazol-2-ylamide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid indan-5-ylamide; -   6-[4-(2-Trifluoromethyl-benzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid pyridin-2-ylamide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid pyridin-3-ylamide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid pyridin-4-ylamide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (6-oxo-1,6-dihydro[1,3,5]triazin-2-yl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (5-fluoro-pyridin-2-yl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (4-cyano-phenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2-cyano-phenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (3-cyano-phenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (5-cyano-pyridin-2-yl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (4,6-dimethylpyrimidin-2-yl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2-chloro-pyridin-4-yl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (1H-indol-6-yl)-amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (1H-indol-4-yl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (1H-indazol-5-yl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (1H-indazol-6-yl)amide, -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (4-methyl-thiazol-2-yl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (5-methyl-thiazol-2-yl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (5-thioxo-4,5-dihydro-1H-[1,2,4]triazol-3-yl)amide; -   6-[4-(2-Trifluoromethylbenzoylpiperazin-1-yl]pyridazine-3-carboxylic     acid (1H-benzoimidazol-2-yl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (6-methylpyridazin-3-yl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (6-methoxypyridazin-3-yl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (3-chloro-phenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (3-chloro-2-methylphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2-chloro-3-methylphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2,5-dichlorophenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2-chloro-5-methylphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2-chloro-6-methylphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (4-chloro-2-methylphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (4-chloro-3-methylphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (3-chloro-4-methylphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2-chloro-4-methylphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2-chloro-5-fluorophenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (5-chloro-2-fluorophenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2,5-difluorophenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2,6-dichlorophenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2-trifluoromethylphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (4-trifluoromethylphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)-piperazin-1-yl]pyridazine-3-carboxylic     acid (3-trifluoromethylphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid phenylamide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (5-chloro-2-methoxyphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2,5-dimethoxyphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2-chloro-4-methoxyphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)-piperazin-1-yl]pyridazine-3-carboxylic     acid (4-methoxyphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (2-methoxyphenyl)amide; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (3-methoxyphenyl)amide; -   4-({6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carbonyl}amino)-benzoic     acid methyl ester; -   4-({6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carbonyl}amino)-benzoic     acid; -   2-({6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carbonyl}amino)-benzoic     acid methyl ester; -   2-({6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carbonyl}amino)-benzoic     acid; -   6-[4-(2-Trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic     acid (3,4-dichlorophenyl)amide; -   1-[1-(4-Fluorophenyl)ethyl]-3-{6-[4-(2-trifluoromethylbenzoyl)piperazin-1-yl]-pyridazin-3-yl}urea.

Example 33 Measuring Stearoyl-COA Desaturase Inhibition Activity of a Test Compound Using Mouse Liver Microsomes

The identification of compounds of the invention as SCD inhibitors was readily accomplished using the SCD enzymes and microsomal assay procedure described in Brownlie et a, PCT published patent application, WO 01/62954.

Preparation of Mouse Liver Microsomes:

Male ICR mice, on a high-carbohydrate, low fat diet, under light halothane (15% in mineral oil) anesthesia are sacrificed by exsanguination during periods of high enzyme activity. Livers are immediately rinsed with cold 0.9% NaCl solution, weighed and minced with scissors. All procedures are performed at 4° C. unless specified otherwise. Livers are homogenized in a solution (1:3 w/v) containing 0.25 M sucrose, 62 mM potassium phosphate buffer (pH 7.0), 0.15 M KCl, 1.5 mM N-acetyleysteine, 5 mM MgCl₂, and 0.1 mM EDTA using 4 strokes of a Potter-Elvehjem tissue homogenizer. The homogenate is centrifuged at 10,400×g for 20 min to eliminate mitochondria and cellular debris. The supernatant is filtered through a 3-layer cheesecloth and centrifuged at 105,000×g for 60 min. The microsomal pellet is gently resuspended in the same homogenization solution with a small glass/teflon homogenizer and stored at −70° C. The absence of mitochondrial contamination is enzymatically assessed. The protein concentration is measured using bovine serum albumin as the standard.

Incubation of Mouse Liver Microsomes with Test Compounds:

Reactions are started by adding 2 mg of microsomal protein to pre-incubated tubes containing 0.20 μCi of the substrate fatty acid (1-¹⁴C palmitic acid) at a final concentration of 33.3 μM in 1.5 ml of homogenization solution, containing 42 mM NaF, 0.33 mM niacinamide, 1.6 mM ATP, 1.0 mM NADH, 0.1 mM coenzyme A and a 10 μLM concentration of test compound. The tubes are vortexed vigorously and after 15 min incubation in a shaking water bath (37° C.), the reactions are stopped and fatty acids are analyzed.

Fatty acids are analyzed as follows: The reaction mixture is saponified with 10% KOH to obtain free fatty acids which are further methylated using BF₃ in methanol. The fatty acid methyl esters are analyzed by high performance liquid chromatography (HPLC) using a Hewlett Packard 1090, Series 11 chromatograph equipped with a diode array detector set at 205 nm, a radioisotope detector (Model 171, Beckman, Calif.) with a solid scintillation cartridge (97% efficiency for ¹⁴C-detection) and a reverse-phase ODS (C-18) Beckman column (250 mm×4.6 mm i.d.; 5 μm particle size) attached to a pre-column with a μBondapak C-18 (Beckman) insert. Fatty acid methyl esters are separated isocratically with acetonitrile/water (95:5 v:v) at a flow rate of 1 mL/min and are identified by comparison with authentic standards. Alternatively, fatty acid methyl esters may be analyzed by capillary column gas-chromatography (GC) or Thin Layer Chromatography (TLC).

Those skilled in the art are aware of a variety of modifications to this assay that can be useful for measuring inhibition of stearoyl-CoA desaturase activity in microsomes by test compounds. For example, this assay may be adapted for high-throughput screening (HTS). Compounds that show good activities by HTS using mouse microsomal assay can be further analyzed, for example using specific enzyme assays to assess their IC50.

As shown in Table 1, representative compounds of the invention showed activity as inhibitors of SCD when tested in these assays. The compounds are analyzed with an HTS microsomal assay. The activities are defined in terms of % SCD enzyme activity remaining at the selected concentration (e.g., 10 μM) of the test compounds. For compounds that show good activities by this HTS assay, they are further analyzed for IC50 values.

Note that the data shown in Table 1 are for representative compounds. One of ordinary skill in the art, with the teachings and various examples shown in this description, would be able to prepare similar compounds, perform the assays, and make use of the compounds without undue experimentation. Therefore, the examples shown are for illustration only and are not intended to limit the scope of the invention.

TABLE 1 Mouse Microsome 10% remaining @ Mouse HEPG2 Compound Name 10 μM IC50 in μM IC50 in μM 6-[4-(4,4,4-Trifluoro-3-methylbut-2- 9% 0.34 0.54 enoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (3-methylbutyl)amide 6-[4-(1-Trifluoromethylcyclopropanecarbonyl)- 26% X X piperazin-1-yl]pyridazine-3-carboxylic acid (3- methylbutyl)amide 6-[4-(4,4,4-Trifluoro-2-methylbutyryl)- 19% X X piperazin-1-yl]pyridazine-3-carboxylic acid (3- methylbutyl)amide 6-[4-(4,4,4-Trifluoro-3-methylbutyryl) 11% X 2.53 piperazin-1-yl]pyridazine-3-carboxylic acid (3- methylbutyl)amide 6-[4-(4,4,4-Trifluorobutyryl)piperazin-1- 42% X X yl]pyridazine-3-carboxylic acid (3- methylbutyl)amide 6-[4-(4-Trifluoromethylpyridine-3- 8% 0.08 0.24 carbonyl)piperazin-1-yl]pyridazine-3- carboxylic acid (3-methylbutyl)amide 6-[4-(1-Methyl-5-trifluoromethyl-1H-pyrazole- 15% 0.35 0.44 4-carbonyl)piperazin-1-yl]-pyridazine-3- carboxylic acid (3-methylbutyl)amide 6-[4-(4-Methylpiperazine-1- 29% X X carbonyl)piperazin-1-yl]pyridazine-3- carboxylic acid (3-methylbutyl)amide 6-[4-(1-Benzyl-5-trifluoromethyl-1H- 61% X X [1,2,3]triazole-4-carbonyl)piperazin-1- yl]pyridazine-3-carboxylic acid (3- methylbutyl)amide 6-[4-(3-Benzyl-5-trifluoromethyl-3H- 61% X X [1,2,3]triazole-4-carbonyl)piperazin-1- yl]pyridazine-3-carboxylic acid (3- methylbutyl)amide 6-[4-(2-Ethylbutyryl)piperazin-1-yl]pyridazine- 36% X X 3-carboxylic acid (2-cyclopropylethyl)amide 6-[4-(3,3,3-Trifluoro-2-methyl-2- 8% 0.11 0.12 trifluoromethylpropionyl)piperazin-1- yl]pyridazine-3-carboxylic acid (2- cyclopropylethyl)amide 6-(4-Cyclohexanecarbonylpiperazin-1- 22% X X yl)pyridazine-3-carboxylic acid (2- cyclopropylethyl)amide 6-[4-(1-Hydroxycyclopropanecarbonyl)- 73% X X piperazin-1-yl]pyridazine-3-carboxylic acid (2- cyclopropylethyl)amide 6-[4-(4,4,4-Trifluoro-3-hydroxy-3- 8% 0.48 0.12 trifluoromethylbutyryl)piperazin-1- yl]pyridazine-3-carboxylic acid (2- cyclopropylethyl)amide 4-[6-(3-Methylbutylcarbamoyl)pyridazin-3- 11% X 1.45 yl]piperazine-1-carboxylic acid t-butyl ester 4-[6-(2-Cyclopropylethylcarbamoyl)pyridazin- 37% X X 3-yl]piperazine-1-carboxylic acid t-butyl ester 6-{4-[2-(2-Trifluoromethylphenyl)acetyl]- 10% 0.59 X piperazin-1-yl}pyridazine-3-carboxylic acid (2- cyclopropylethyl)amide 6-[4-(Pyridine-2-carbonyl)piperazin-1- 94% X X yl]pyridazine-3-carboxylic acid (2- cyclopropylethyl)amide 6-[4-(2-Ttrifluoromethylfuran-3- 7% 0.26 0.29 carbonyl)piperazin-1-yl]pyridazine-3- carboxylic acid (2-cyclopropylethyl)amide 6-[4-(5-Chloro-2-trifluoromethylbenzoyl)- 12% 0.09 0.04 piperazin-1-yl]pyridazine-3-carboxylic acid (2- cyclopropylethyl)amide 6-[4-(2,5-Bis-trifluoromethylbenzoyl)piperazin- 6% 0.15 0.07 1-yl]pyridazine-3-carboxylic acid (2- cyclopropylethyl)amide Acetic acid 2-{4-[6-(2-cyclopropylethyl 46% X X carbamoyl)-pyridazin-3-yl]piperazine-1- carbonyl}phenyl ester 6-[4-(2-Trifluoromethylbenzoyl)piperazin-1- 0% 0.02 0.02 yl]pyridazine-3-carboxylic acid phenethylamide 6-[4-(2-Nitrobenzoyl)piperazin-1- 8% 0.08 0.12 yl]pyridazine-3-carboxylic acid (3- methylbutyl)amide 6-[4-(2-Aminobenzoyl)piperazin-1- 23% 0.45 0.64 yl]pyridazine-3-carboxylic acid (3- methylbutyl)amide 4-Methyl-2-({6-[4-(2-trifluoromethylbenzoyl)- 69% X X piperazin-1-yl]-pyridazine-3- carbonyl}amino)pentanoic acid methyl ester 6-[4-(2-Trifluoromethylbenzoyl)piperazin-1- 49% 8.69 5.52 yl]pyridazine-3-carboxylic acid cyclopropylmethylamide 6-[4-(2-Trifluoromethylbenzoyl)piperazin-1- 7% 1.63 0.08 yl]pyridazine-3-carboxylic acid [2-(4- methoxyphenyl)ethyl]amide 6-[4-(2-Trifluoromethylbenzoyl)piperazin-1- 5% 0.02 0.02 yl]pyridazine-3-carboxylic acid [2-(2,4- fluorophenyl)ethyl]amide 1-[1-(4-Fluorophenyl)ethyl]-3-{6-[4-(2- 45% X X trifluoromethylbenzoyl)piperazin-1- yl]pyridazin-3-yl}urea 1-[3-(4-Fluorophenyl)propyl]-3-{6-[4-(2- 14% 1.37 0.35 trifluoromethylbenzoyl)piperazin-1- yl]pyridazin-3-yl}urea 3-(3-{6-[4-(2-Trifluoromethylbenzoyl)- 18% 2.77 5.43 piperazin-1-yl]-pyridazin-3-yl}ureido)propionic acid ethyl ester 1-Pentyl-3-{6-[4-(2-trifluoromethylbenzoyl)- 6% 0.01 0.04 piperazin-1-yl]pyridazin-3-yl}urea 1-Benzyl-3-{6-[4-(2-trifluoromethylbenzoyl)- 8% 0.04 0.05 piperazin-1-yl]pyridazin-3-yl}urea 1-(4-Fluorophenyl)-3-{6-[4-(2-trifluoromethyl- 82% X X benzoyl)piperazin-1-yl]-pyridazin-3-yl}urea 1-(2-Fluorophenyl)-3-{6-[4-(2-trifluoromethyl- 73% X X benzoyl)piperazin-1-yl]pyridazin-3-yl}urea 1-Phenethyl-3-{6-[4-(2-trifluoromethyl- 15% 0.06 0.23 benzoyl)piperazin-1-yl]-pyridazin-3-yl}urea 1-(4-Fluorobenzyl)-3-{6-[4-(2-trifluoromethyl- 6% 0.07 0.03 benzoyl)piperazin-1-yl]pyridazin-3-yl}urea 1-Butyl-3-{6-[4-(2-trifluoromethylbenzoyl)- 13% 0.07 0.21 piperazin-1-yl]pyridazin-3-yl}urea 6-[4-(2-Trifluoromethylbenzyl)piperazin-1- 12% 0.09 0.04 yl]pyridazine-3-carboxylic acid (2- cyclopropylethyl)amide 6-[4-(5-Fluoro-2-trifluoromethylbenzyl)- 3% 0.02 0.02 piperazin-1-yl]pyridazine-3-carboxylic acid (2- cyclopropylethyl)amide 6-[4-(4-Fluoro-2-trifluoromethylbenzyl)- 12% 0.02 0.01 piperazin-1-yl]pyridazine-3-carboxylic acid (2- cyclopropylethyl)amide 6-[4-(5-Chloro-2-trifluoromethylbenzyl)- 7% 0.06 0.04 piperazin-1-yl]pyridazine-3-carboxylic acid (2- cyclopropylethyl)amide 6-[4-(2-Chloro-4-fluorobenzyl)piperazin-1- 11% 0.13 0.07 yl]pyridazine-3-carboxylic acid (2- cyclopropylethyl)amide 6-[4-(2,5-Dichlorobenzyl)piperazin-1- 8% 0.18 0.06 yl]pyridazine-3-carboxylic acid (2- cyclopropylethyl)amide 6-[4-(2,4-Dichlorobenzyl)piperazin-1- 8% 0.23 0.21 yl]pyridazine-3-carboxylic acid (2- cyclopropylethyl)amide 6-[4-(5-Fluoro-2-trifluoromethylbenzyl)- 8% 0.18 0.06 piperazin-1-yl]pyridazine-3-carboxylic acid (3- cyclopropylpropyl)amide 6-{4-[1-(2-Trifluoromethylphenyl)- 24% X X ethyl]piperazin-1-yl}-pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide

Example 34 Assessing the Effect of a Topically Administered LCF369 (Example 3.13) on the Sebaceous Glands of NMRI Mice

Because SCDs (particularly, SCD-1) play important roles in fat cell metabolism, it may be possible to control the functions of sebaceous glands by controlling the activities of SCDs. As noted above, it has been shown that atrophy of sebaceous glands could be induced by inhibiting the activity of SCD that is expressed in sebaceous glands in mice (Zheng et al., Nature Genet. 23:268-270, 1999). In addition, mice with loss of gene function (SCD-1−/− mice) develop atrophic sebaceous and meibomian glands (Miyazaki et al., J. Nutr. 131:2260-2268, 2001). Therefore, inhibition of sebum production by the sebaceous glands through inhibition or modulation of SCD may be used to effectively prevent or treat skin diseases that arise from excessive sebum production.

As shown in Table 1, compounds of the invention are effective inhibitors of SCD. Therefore, they are expected to be useful in the treatment or prevention of skin diseases. The usefulness of these compounds is demonstrated below using a representative compound, LCF369 (Example 3.13; 6-[4-(5-Fluoro-2-trifluoromethylbenzoyl)piperazin-1-yl]pyridazine-3-carboxylic acid (2-cyclopropylethyl)amide). Although the following examples are shown with LCF369, other compounds of the invention will have the same effects.

Methods

LCF369 is prepared either in a solution of ethanol/propylene glycol (3/7, v/v) or in topical formulations at 1.0, 0.5 or 0.1% for testing in female Crl:NMRI mice. In general, shaved application sites of approximately 2.5 cm² on the back of mice are treated twice daily (once on weekends or at study termination) with 50 μl of the LCF369 preparations. To prevent the animals from potential oral uptake of the epicutaneously applied compounds, they are fitted with ruffs and housed individually. After the last application, the animals are euthanised; the treated sites dissected and prepared for histological sections. Hematoxilin/eosin (HE)-stained 3 μm-thick sections are prepared from formalin-fixed, paraffin-embedded tissue. From each animal, one HE-stained section per site is histomorphometrically examined. The entire sections of approximately 10 mm length are evaluated microscopically (200×) for sebaceous glands. The mean size and mean number (per mm² dermis) of sectioned alveolar units of the sebaceous glands are determined in a coded fashion with an image analyzer (Axiovision, Zeiss). For statistical analysis, morphometric data are analyzed with a T-test or Mann-Whitney rank sum test. Frozen tissue sections (5 μm) are used for oil red O (lipid) staining.

1. Evaluation of Efficacy:

Groups of 5 mice are treated with 50 μl of 1% or 0.1% LCF369 twice daily (except on weekends, when the animals are treated once daily and on study termination) for 8 days (i.e. 14 applications in total). Four control animals are treated similarly with the vehicle alone. In life, the animals are observed for clinical signs and macroscopic changes of the application sites. One day after the last application, an evaluation is performed. In animals treated with 1.0% LCF369, untreated skin samples distant from the treated sites are also collected in order to assess systemic activity due to percutaneous absorption of LCF369.

TABLE 2 Mean number and mean size of sebaceous glandular units in LCF369- untreated and treated mice after an 8-days treatment period Number of Size of Days of sebaceous sebaceous Treatment treatment glandular units glandular units 1.0% LCF369 (locally) 8   13.7 (8.2)***   571 (200)** 0.1% LCF369 (locally) 8 34.3 (4.1) 1090 (200) Vehicle (locally) 8 38.1 (8.0) 1050 (130) 1.0% LCF369 8 28.4 (6.0) 1090 (250) (distantly) Vehicle (distantly) 8 32.8 (3.9) 1100 (160) Note: LCF369 is applied daily for 8 consecutive days (in total 14 applications). Number of sebaceous glandular units per mm² dermis and mean size (μm²) are histomorphometrically determined in treated sites (locally) and in sites distant form the treated sites (distantly) on day 9. Mean (SD) values of 5 (LCF groups) or 4 (vehicle group) animals; **p < 0.01, ***p < 0.001 vs vehicle (locally)

The mean numbers and mean sizes (with standard deviations, SD, shown in parentheses) of sebaceous glandular units in the LCF369 treated and untreated mice after 8 days are shown in Table 2. The number of sebaceous glandular units per mm² and mean size (μm²) were histomorphometrically determined in treated sites (locally) and at sites distant from the treated sites (distantly) on day 9. As shown in Table 2, application of 1.0% LCF369 reduces the sebaceous glands in numbers by a factor of about 2.5 (p<0.001) and by about 1.9 fold (p<0.01) in sizes.

The effect of LCF369 is concentration (dose) dependent because treatments with 0.1% LCF369 induce little or no atrophogenic effects (Table 2). There are no significant differences in the numbers and sizes of the sebaceous glands at sites distant from the LCF369 treatments (Table 2). This finding indicates that the efficacies of treatments with 1.0% LCF369 are restricted to the treated area, suggesting that topical administration of LCF369 does not induce percutaneous absorption or systemic effects.

FIG. 2A and FIG. 2B show representative histochemical stainings of skin samples from untreated (vehicle-treated) and LCF369-treated areas, respectively. The skin sections (3 μm thick) are prepared from formalin-fixed, paraffin-embedded tissue and are stained with hematoxilin and eosin (HE). The arrows in these Figures indicate the sebaceous glands. It is apparent that the untreated skin (FIG. 2A) has more and larger sebaceous glands, as compared with the LCF369 treated skin (FIG. 2B), which shows fewer and smaller (atrophic) sebaceous glands.

FIG. 3A and FIG. 3B show cryosection skin samples stained with oil red O for the untreated (vehicle-treated) and LCF369-treated areas, respectively. Oil red O is a stain for lipids or fats. As shown in FIG. 3A, hair shafts are clearly associated with lipids (secreted by sebaceous glands) without LCF369 treatment, as indicated by arrows. In contrast, FIG. 3B shows that LCF369 treatment results in significantly reduced lipids associated with hair shafts (shown by arrow). Thus, the reduction in the number and size of sebaceous glands in the treated skins is associated with reduced production of sebum, as evidenced by the reduced amounts of lipids in the sebaceous gland areas. The reduction in lipid production results from the inhibition of SCD, which is known to play an important role in various lipid or fat productions. Compounds of the invention are effective inhibitors of SCD, and therefore they are effective agents for the treatment or prevention of skin disorders mediated by SCD. Although, the above results are shown with LCF369, other compounds are expected to have similar results, as evidenced by their effective inhibitions of SCD (see Table 1).

2. Determination of the Minimal Treatment Period

Groups of 4 mice are treated with 1.0% LCF369 twice daily for 2, 4, 6 and 8 days (i.e. up to 16 applications). Control groups remain untreated or are treated with the vehicle alone twice daily for 8 days.

TABLE 3 Mean number and mean size of sebaceous glandular units in mice treated topically with LCF369 for 2, 4, 6 or 8 days Number of Size (μm²) of Days of sebaceous glandular sebaceous glandular Treatment treatment units units 1.0% LCF369 2 24.8 (1.3)+ 1095 (211)+ 1.0% LCF369 4 18.0 (6.8)**  875 (215)* 1.0% LCF369 6 12.6 (5.1)***  613 (171)*** 1.0% LCF369 8  7.0 (2.0)***  374 (199)*** Vehicle 8 27.7 (3.1) 1354 (248) Untreated — 24.1 (3.4) 1461 (303) Note: LCF369 is applied twice daily for 2 to 8 days. Number of sebaceous glandular units per mm² dermis and mean size (μm²) are histomorphometrically determined at sites treated with LCF369 or vehicle or at untreated sites one day after the last application. +Mean (SD), 4 animals per group, *p < 0.05; **p < 0.01, ***p < 0.001 vs. vehicle controls

As shown in Table 3, treatments with LCF369 twice daily for 8 days lead to progressive decrease in the size (19%) and numbers (12%) of sebaceous glands, as compared with treatments with the vehicle. The effect of treatment increases with time and is statistically significant after 4 days (8 applications). The mean size decreases by 35% after 4 days, by 35% after 6 days, and by 72% after 8 days. Similarly, the numbers of sebaceous glands are reduced by 35% after 4 days, by 54% after 6 days, and by 75% after 8 days.

3. Determination of the Minimal Effective Concentration:

LCF369 is tested at 1.0%, 0.5% and 0.1%, groups of 6 mice are treated twice daily for 7 consecutive days. Evaluation is performed on the day following the 14^(th) application.

TABLE 4 Mean number and mean size of sebaceous glands at sites treated topically with various concentrations of LCF369 twice daily for 7 days Number of Size (μm²) of Concentration sebaceous sebaceous Treatment (w/v) glandular units glandular units LCF369 1.0% 10.1 (4.0)***  675 (299)*** LCF369 0.5% 14.5 (5.2)**  870 (190)*** LCF369 0.1% 23.8 (3.4)^(ns) 1396 (333)^(ns) Vehicle 0 23.4 (4.2) 1678 (310) Note: LCF369 was applied twice daily for 7 days. Number of sebaceous glandular units per mm² dermis and mean size (μm²) are histomorphometrically determined in sites treated with LCF369 or vehicle one day after the last application. +Mean (SD), 6 animals per group, ^(ns)not statistically different, *p < 0.05; **p < 0.01, ***p < 0.001 vs. vehicle controls.

As shown in Table 4, topical applications of LCF369 at 1.0%, 0.5% and 0.1% result in a concentration-dependent atrophy of the sebaceous glands at the treated sites within 1 week. The minimal statistically significant effective concentration is 0.5% LCF369 when applied twice daily (50 μL each time) for 7 days. One of ordinary skill in the art would appreciate that the effective concentration would vary depending on the amount (volume) of application each time. Therefore, while under this experimental condition (50 μL each time), 0.5% LCF369 seems to be the minimally effective concentration (50 μL×0.5%=0.25 mg per application). Under different conditions, different concentrations may be used (e.g., lower concentrations with larger volumes per application). As shown in Table 4, at 0.5% LCF369, the numbers of sebaceous glands per mm² dermis is reduced by 38% and the mean size is reduced by 48%. At 1% LCF369, the reductions are by 57% in numbers and by 60% in size (compared with vehicle-treated controls).

4. Determination of Duration of Action:

A 7-day b.i.d. (twice daily) treatment schedule (except on week ends when the animals were treated once daily) with 1.0% LCF369 is applied to groups of 7 mice which are evaluated on days 8 (one day after the 14^(th) application), 24 and 41. For comparison, skin sections from animals treated with vehicle are examined on day 8 and skin samples from untreated animals of the same delivery were examined in parallel on days 8 and 41.

TABLE 5 Recovery in mean number and mean size of sebaceous glandular units at test sites pre-treated with LCF369 Day of Number of sebaceous Size (μm²) of Treatment evaluation glandular units sebaceous glandular units LCF 1% 8 9.28 (4.03)***  708 (271)** Vehicle 8 22.9 (3.98)^(n.s.) 1730 (486) untreated 8 21.1 (1.45) 1407 (251) LCF1% 24 17.4 (4.55) 1154 (162) LCF1% 41   21 (2.1) 1456 (151) untreated 41   25 (8.24) 1211 (239) Note: Mean number and size (SD) of sebaceous glandular units in treated areas are compared with sebaceous glandular in vehicle-treated sites or untreated sites one (day 8), 17 days (day 24) and 34 days (day 41) after the last application of a 7-day treatment period LCF369; 7 animals per group, ^(ns)not statistically different, **p < 0.01, ***p < 0.001 vs vehicle-treated controls.

As shown in Table 5, one day after the 7 days-treatment period with 1% LCF369, the numbers and mean size of sebaceous glands are reduced by 57% and 50%, respectively. Treatment with the vehicle alone caused no significant effect, as compared to the untreated sites. The atrophogenic effect from LCF369 treatment is substantially reduced on day 24 and almost completely absent on day 41. This observation indicates that the effect of LCF369 can last for several days after the last application.

5. Efficacy Studies with Clinical Service Form Candidates:

Three different formulations containing 0.5% LCF369 are tested; i) emulsion gel with the penetration enhancer Sepa 09 (batch 92.66.01-ra), ii) emulsion gel without a penetration enhancer (batch 9450-05-Ra), and iii) a formulation containing particulate compound (“follicular targeting formulation”). They are evaluated after 9 or 13 applications.

TABLE 6 Mean number and mean size of sebaceous glandular units in test sites treated with a 0.5% LCF369 formulation containing SEPA-9 Size (μm²) Number of Number of sebaceous of sebaceous Treatment applications glandular units glandular units Vehicle 13× 21.8 (4.5)  2611 (184.8) LCF369 0.5%  9× 10.6 (5.89)* 745.8 (339.3)*** LCF369 0.5% 13× 10.1 (3.48)* 946.1 (134.0)*** Note: Mean number and size (SD) of sebaceous glandular units in treated areas were compared with sebaceous glandular units in sites treated 13× with vehicle. 3 animals per group, *p < 0.05, ***p < 0.001 vs vehicle-treated controls.

As shown in Table 6, treatment with the formulation containing the penetration enhancer SEPA-9 (or SEPA 0009; 2-n-nonyl-1,3-dioxolane) resulted in a significant atrophy of sebaceous glands. The results are similar after 9 and 13 applications, indicating that the effect of 0.5% LCF369 has peaked after 9 applications. Compared with the results shown in Table 3, which shows that the effects of 1% LCF369 are still increasing after 6 days (12 applications), these results suggest that the penetration enhancer appreciably speeds up the effects of LCF369. Therefore, compounds of the invention may benefit from the use of a penetration enhancer. In sections of samples treated with LCF369, hyper/parakeratosis and acanthosis is more pronounced than in placebo-treated (vehicle-treated) samples.

Any penetration enhancer known in the art may be used, including for example fatty acids, fatty acid esters, fatty alcohols, glycols and glycol esters, 1,3-dioxolanes and 1,3dioxanes, macrocyclic ketones containing at least 12 carbon atoms, oxazolidinones, and oxazolidinone derivatives, alkyl-2-(N,N-disubstituted amino)-alkanoate esters, (N,N-disubstituted amino)-alkanol alkanoates, and mixtures thereof. Preferably, the dermal penetration enhancer is selected from the list including oleic acid, oleyl alcohol, cyclopentadecanone (CPE-218™), sorbitan monooleate, glycerolmonooleate, propylene glycolmonolaurate, polyethylene glycolmonolaurate, 2-n-nonyl 1,3-dioxolane (SEPA), dodecyl2-(N,N-dimethylamino)-propionate (DDAIP) or its salt derivatives, 2-ethylhexyl 2-ethylhexanoate, isopropyl myristate, dimethyl isosorbide, 4-decyloxazolidinon-2-one (SR-38w, TCPI, Inc.), 3-methyl-4-decyloxazolidinon-2-one, and mixtures thereof. See, EP patent application publication No. EP1534235; See also, E. W. Smith et al., “Percutaneous Penetration Enhancers,” 2^(nd) edition, Culinary and Hospitality Industry Publications Services.

The results from the penetration enhancer suggest other ways to deliver compounds of the invention in topical applications may be beneficial. One approach to enhanced topical delivery is via “follicular targeting.” Hair follicles increase surface area and disrupt the epidermal barrier towards the lower parts of the hair follicle. Thus, hair follicle serves not only as a reservoir, but also as a major entry point for topically applied compounds. Various drug carrier and drug delivery systems are currently being investigated as follicular targeting agents or systems. See, A. Vogt et al., “Follicular Targeting—A Promising Tool in Selective ermatotherapy,” Journal of Investigative Dermatology Symposium Proceedings (2005) 10, 252-255.

In a side-by-side comparison of the activities of the “follicular targeting form” containing drug in suspension and an emulsion gel without a penetration enhancer, the suspension formulation is inactive (Table 7). Although placebos cannot be included in that study, results from animals treated with the suspension formulation equal those from untreated animals in earlier studies. Results shown in Table 7 indicate that treatment with the enhancer free emulsion gel results in a reduction by 49% in numbers and by 63% in size (p<0.01), as compared to the suspension formulation.

TABLE 7 Mean number and size of sebaceous gland units in murine skin after 9 topical application of 0.5% LCF369 prepared in a suspension formulation and in an emulsion gel without penetration enhancer Number of Size (μm²) of Treatment sebaceous glandular units sebaceous glandular units Suspension 26.1 (5.0)  1150 (324)  formulation Enhancer-free 13.3 (7.6)** 427 (305)** emulsion gel +: of sebaceous gland units per mm²; **p < 0.01 vs the suspension formulation

The above examples show that compounds of the invention are effective agents for the treatment and prevention of skin disorders that are associated with excess fat or lipid production, i.e., mediated by SCD. Compounds of the invention may be prepared in any suitable dosage forms, including solutions, suspensions, emulsions, gel, paste, tablets, injections, patches, sprays, etc. Methods for preparing these formulations are well known to one skilled in the art.

These compounds when applied topically, their atrophogenic effects are concentration- and time-dependent (e.g., with LCF369, the efficacy is seen at ≧0.4% and ≧4 day) and is reversible. Maximum reduction in sizes and numbers can he up to 75%, as compared to untreated skin. The activity of a compound of the invention (e.g., LCF369) is shown to be due to a local action at the application site.

The therapeutically effective amounts of compounds of the invention will depend on the formulations, dosage forms, routes of administration, conditions and natures of the skin disorders, subject body weights, body conditions, and ages. However, optimization of these parameters involve only routine skills for one skilled in this art and would not require undue experimentation. As a general guideline, if administered orally, a proper dosage may be less than about 100 mg/kg body weight, for example less than about 50 mg/kg, less than about 10 mg/kg, less than about 5 mg/kg, or less than about 2 mg/kg. If administered topically, these compounds may be prepared as a formulation containing any suitable concentrations of the compounds, for example, about 50% or less, about 20% or less, about 10% or less, about 5% or less, about 3% or less, about 2% or less, or about 1% or less.

If used in a topical formulation, compounds of the invention may be used with or without a percutaneous penetration enhancer. Any suitable enhancer known in the art may be used. The enhancer may be used at any suitable concentrations, for example less than about 50% (w/v), less than about 20%, less than about 10%, less than about 5%, or less than about 1%. Note that the specific numbers mentioned above are examples. Any numbers inbetween these specific numbers may also be used and therefore are intended to be included.

From the foregoing it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention. Accordingly, the invention is not limited except as by the appended claims. 

1. A method of treating a skin disorder mediated by stearoyl-CoA desaturase (SCD) in a mammal selected from the group consisting of acne, rosacea, seborrheic skin, and a combination thereof, wherein the method comprises administering to the mammal in need thereof a therapeutically effective amount of a compound of formula (I):

wherein: x and y are each independently 1; W is —C(O)N(R¹)—; —C(O)N[C(O)R^(1a)]—, —N(R¹)C(O)N(R¹)— or —N(R¹)C(O)—; V is —C(O)—, —C(S)—, or —C(R¹⁰)H; each R¹ is independently selected from the group consisting of hydrogen; C₁-C₆alkyl optionally substituted with one or more substituents selected from the group consisting of halo, methyl or trifluoromethyl; and C₂-C₆alkyl optionally substituted with one or more substituents selected from the group consisting of methoxy and hydroxyl; R^(1a) is selected from the group consisting of hydrogen, C₁-C₆alkyl and cycloalkyl; R² is selected from the group consisting of C₁-C₁₂alkyl, C₂-C₁₂alkenyl, C₂-C₁₂hydroxyalkyl, C₂-C₁₂hydroxyalkenyl, C₁-C₁₂alkoxy, C₂-C₁₂alkoxyalkyl, C₃-C₁₂cycloalkyl, C₄-C₁₂cycloalkylalkyl, aryl, C₇-C₁₂aralkyl, C₃-C₁₂heterocyclyl, C₃-C₁₂heterocyclylalkyl, C₁-C₁₂heteroaryl, and C₃-C₁₂heteroarylalkyl; or R² is a multi-ring structure having 2 to 4 rings wherein the rings are independently selected from the group consisting of cycloalkyl, heterocyclyl, aryl and heteroaryl and where some or all of the rings may be fused to each other; R³ is selected from the group consisting of C₁-C₁₂alkyl, C₂-C₁₂alkenyl, C₂-C₁₂hydroxyalkyl, C₂-C₁₂hydroxyalkenyl, C₁-C₁₂alkoxy, C₂-C₁₂alkoxyalkyl, C₃-C₁₂cycloalkyl, C₄-C₁₂cycloalkylalkyl, aryl, C₇-C₁₂aralkyl, C₃-C₁₂heterocyclyl, C₃-C₁₂heterocyclylalkyl, C₁-C₁₂heteroaryl and C₃-C₁₂heteroarylalkyl; or R³ is a multi-ring structure having 2 to 4 rings wherein the rings are independently selected from the group consisting of cycloalkyl, heterocyclyl, aryl and heteroaryl and where some or all of the rings may be fused to each other; R⁴ and R⁵ are each independently selected from hydrogen, fluoro, chloro, methyl, methoxy, trifluoromethyl, cyano, nitro or —N(R¹²)₂; R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each independently selected from hydrogen or C₁-C₃alkyl; or R⁶ and R^(6a) together, or R⁷ and R^(7a) together, or R⁸ and R^(8a) together or R⁹ and R^(9a) together are an oxo group, provided that when V is —C(O)—, R⁷ and R^(7a) together, or R⁸ and R^(8a) together, do not form an oxo group; or one of R⁶, R^(6a), R⁷, and R^(7a) together with one of R⁸, R^(8a), R⁹ and R^(9a) form an alkylene bridge; R¹⁰ is hydrogen or C₁-C₃alkyl; and each R¹² is independently selected from hydrogen or C₁-C₆alkyl; a stereoisomer, enantiomer or tautomer thereof, a pharmaceutically acceptable salt thereof, or a pharmaceutical composition thereof.
 2. The method of claim 1, wherein the mammal is a human.
 3. The method of claim 1, wherein the administering is by topical administration.
 4. The method of claim 1, wherein the pharmaceutical composition of the compound of formula (I) comprises a percutaneous penetration enhancer.
 5. The method of claim 4, wherein the percutaneous penetration enhancer is SEPA-9.
 6. The method of claim 1, wherein the skin disorder is rosacea.
 7. The method of claim 1, wherein the skin disorder is seborrheic skin.
 8. The method of claim 1, wherein V is —C(O)— or —C(S)—; W is selected from —C(O)N(R¹)— and —N(R¹)C(O)—; R² is selected from the group consisting of C₁-C₁₂alkyl, C₂-C₁₂alkenyl, C₂-C₁₂hydroxyalkyl, C₂-C₁₂hydroxyalkenyl, C₁-C₆alkoxy, C₃-C₁₂alkoxyalkyl, C₃-C₁₂cycloalkyl, C₄-C₂cycloalkylalkyl, aryl, C₇-C₁₂aralkyl, C₃-C₁₂ heterocyclyl, C₃-C₁₂heterocyclylalkyl, C₁-C₁₂heteroaryl and C₃-C₁₂heteroarylalkyl; R³ is phenyl optionally substituted by one or more substituents selected from the group consisting of halo, cyano, nitro, hydroxy, C₁-C₆alkyl, C₁-C₆trihaloalkyl, C₁-C₆trihaloalkoxy, C₁-C₆alkylsulfonyl, —N(R¹¹)₂, —OC(O)R¹¹, —C(O)OR¹¹, —S(O)₂N(R¹¹)₂, cycloalkyl, heterocyclyl, heteroaryl and heteroarylcycloalkyl, provided that R³ is not phenyl substituted with optionally substituted thienyl; R⁴ and R⁵ are each independently selected from hydrogen, fluoro, chloro, methyl, methoxy and trifluoromethyl; and R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each independently selected from hydrogen or C₁-C₃alkyl.
 9. The method of claim 1, wherein V is —C(O)—; W is selected from —C(O)N(R¹)— and —N(R¹)C(O)—; R² is selected from the group consisting of C₇-C₁₂alkyl, C₃-C₁₂alkenyl, C₇-C₁₂hydroxyalkyl, C₂-C₁₂alkoxyalkyl, C₃-C₁₂hydroxyalkenyl, C₃-C₁₂cycloalkyl, C₄-C₁₂cycloalkylalkyl, C₃-C₉aralkyl, C₃-C₁₂heterocyclylalkyl, and C₃-C₁₂heteroarylalkyl; R³ is selected from the group consisting of C₃-C₁₂alkyl, C₃-C₁₂alkenyl, C₃-C₁₂hydroxyalkyl, C₃-C₁₂hydroxyalkenyl, C₃-C₁₂alkoxy, C₃-C₁₂alkoxyalkyl, C₃-C₁₂cycloalkyl, C₄-C₁₂cycloalkylalkyl, aryl, C₇-C₁₂aralkyl, C₃-C₁₂heterocyclyl, C₃-C₁₂heterocyclylalkyl, C₅-C₁₂ heteroaryl and C₃-C₁₂heteroarylalkyl; R⁴ and R⁵ are each independently selected from hydrogen, fluoro, chloro, methyl, methoxy and trifluoromethyl; and R⁶, R^(6a), R⁷, R^(7a), R⁸, R^(8a), R⁹, and R^(9a) are each independently selected from hydrogen or C₁-C₃alkyl.
 10. The method of claim 9, wherein: V is —C(O)—; W is —N(R¹)C(O)—; R² is C₃-C₁₂cycloalkyl; R³ is aryl or C₅-C₁₂heteroaryl.
 11. The method of claim 10, wherein the skin disorder is rosacea.
 12. The method of claim 10, wherein the skin disorder is seborrheic skin. 